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THE PSYCHOLOGY OF 
REASONING 

BASED ON 

EXPERIMENTAL RESEARCHES IN 

HYPNOTISM 

BY \/ 

ALFRED BINET 

v 

DOCTOR OF SCIENCE, LAUREATE OF THE INSTITUTE (ACADEMIE DES SCIENCES 
AND ACADEMIE DES SCIENCES MORALES) 

DIRECTOR OF THE LABORATORY OF PHYSIOLOGICAL rSVCHOLOGY IN 
THE SOKBONNE (hAUTES ETUDES) 



TRANSLATED FROM THE SECOND FRENCH EDITION 
BY ADAM GOWANS WHYTE, B. SC. 



CHICAGO 
THE OPEN COURT PUBLISHING COMPANY 

London: Kegan Paul, Trench, Trubner & Co. 
1899 



-> r 






35582 



Copyright, 1899 
By the open COURT PUBLISHING COMPANY 



Ali rights reserved 






R, R. DONNELLEY & SONS COMPANY 
CHICAGO 






TO 

DOCTOR CHARLES FERE 

PHYSICIAN IN THE SALPETRIERE, BY HIS FRIEND 

ALFRED BINET 



CONTENTS. 



CHAPTER I. 
The Definition of Perception, 

PAGES 

Statement of the problem. — Ancient theory of proof. — Per- 
ception is produced by the cooperation of the senses 
and the mind. — Perception consists of an association of 
sensations and images. — Examples of illusions of the 
senses i 

CHAPTER n. 

Images. 

First: The definition of images. — The indifferent type. — 
The visual type. — The auditory type. — The motor 
type. Second: The physiological theory of images. — 
Images result from an excitation of the sensory centers 
of the cerebral surface layers. Third: The image 
compared with the consecutive sensation of sight. . . lo 

CHAPTER III. 

Reasoning in Perception. 

First: Properties of images associated with sensations — 
Experiments on hypnotic hallucination. Second: Per- 
ception results from an operation of synthesis. — Gen- 
eric perception and individual perception. — These two 
kinds of perception are only different phases of the 
same process. — Proofs drawn from hypnotic experi- 
ments on systematized anaesthesia. Third: Percep- 
tion is a reasoning. — Comparison of perception with 
the syllogism. — Helmholtz's opinion. — The illusion is a 
sophism. Fourth : To what conditions must an ex- 
planation of reasoning be subject? — Discussion of 
Mr. Spencer's theory 56 



CHAPTER IV. 
The Mechanism of Reasoning. 

PAGES 

First : The law of fusion. — The total fusion of sensations 
in Weber's experiment. — The partial fusion in the 
zootrope. — The partial fusion of images in the cases of 
Henslow and of Goethe. — The partial fusion of images 
in the formation of general ideas. — Comparisons drawn 
from Gallon's generic images. — Physiological expres- 
sion of the law of fusion. Second: The fusion of sen- 
sations and of images. — Hypnagogic hallucinations.— 
Toxic hallucinations. — Voluntary and involuntary illu- 
sions. — Analysis of a simple perception. — Every per- 
ception is an operation in three terms. Third: 
Proofs drawn from complex perceptions. — New com- 
parison between perception and the syllogism. — Theory 
of three images 102 

CHAPTER V. 
Conclusion. 

First : Logical reasonings have the same mechanism as 
perceptive reasoning. — New arrangement of the syllo- 
gistic propositions. Second : Reasoning compared to 
a supplementary sense. Third : Reasoning is the 
single type of all intellectual operations. Fourth : 
Reasoning is an organization of images. — Physiolog- 
ical theory of reasoning 158 



CHAPTER I. 

THE DEFINITION OF PERCEPTION. 

The important modifications which were undergone 
some years ago by the theory of proof stated by 
Aristotle, and considered for two thousand years as 
an impregnable truth, are well known. According 
to the ancient logicians, a syllogism — that is, a 
group of three propositions, the first of which is gen- 
eral — constitutes a proof. In the syllogism, "All 
men are mortal, Paul is a man, therefore Paul is 
mortal," the particular conclusion that Paul, actu- 
ally living, is subject to death, is proved by the 
major "all men are mortal," because it is contained 
in the major. Such is the essence of proof; the 
particular case is considered as proved when it is 
contained in the general case, as a small circle 
within a larger circle ;* and consequently reasoning 
is false whenever the conclusion is not contained 
within the premisses. Stuart Mill was the first to 
show that if it were really so, if the conclusion were 
contained in the premisses, reasoning would be 
valueless, it would teach us nothing, it would not 
be an instrument of discovery, but a repetition 
under an altered form of knowledge already 
acquired. In other words, it would be "solemn 

*Euler, materializing this conception, represented the syllogism by 
three circles of different areas, and enclosed one within another. Lettres 
a une Princesse d'Allemag-ne, ciii et seq. 



2 THE PSrCHOLOGT OF REASONING. 

trifling." The one useful operation consists in 
joining to one fact a second fact not contained in 
the first. 

It is admitted, however, that reasoning supplies 
us every day with the knowledge of new truths. 
We learn a new truth when we discover that Paul is 
mortal, and we discover it by the aid of reasoning, 
since, Paul being yet alive, we are unable to learn 
it by direct observation.* Stuart Mill has replaced 
the scholastic and purely nominal theory of proof 
by another theory which is entirely positive. He 
has considered it sufificient to remark that the major 
proposition of the peripatetic syllogism is not 
general, or at least that the general proposition is 
not the proof of the conclusion. If we are justified 
in affirming that Paul is mortal, it is because 
John, Thomas and the rest are dead; it is because 
all Paul's ancestors and all their contemporaries are 
dead. These numerous, though always particular 
facts are the real premisses of reasoning, the real 
proofs of the conclusion. So that the conclusion is 
not contained in the premisses; it is distinct from 
them and adds something more to them. 

This idea, wjiich is so appropriate, simple and 
natural, explains how reasoning constitutes a devel- 
opment of knowledge, since every inference leads 
from one particular to another and thus adds new 
and previously unobserved facts to facts already 
known. But this point of view has given rise to a 
problem which has not yet been stated and which 

'^WCi^, Logic. Cf. Taine English Positivis7n, p. 34; Brochard Logique 
de Stuart Mill {Reznie philoso^higjie, tome xii) and Paul Janet {ibid.) 



DEFINITION OF PERCEPTION. % 

has remained until now unsolved. How can one 
particular fact prove another particular fact? The 
old theory of the syllogism had the merit of show- 
ing, although by a rough simile, the manner in 
which the conclusion was proved. ' It was proved 
because it was contained in a more general truth, 
by a phenomenon akin to the incasement of seeds, 
and the whole mental effort in reasoning was 
engaged upon drawing, in bringing to light and 
extracting these conclusions from the premisses, 
which enclosed them like large envelopes. But as 
soon as the terms can no longer be considered as 
containing one another, and the circles of Euler 
cease to represent the operations of the mind, it 
becomes necessary to find a new theory of proof. 

The mental process in the case of external per- 
ception belongs to the class of unconscious reason- 
ings. But little importance need be attached to this 
characteristic ; for there is really only one method 
of reasoning, and the study of unconscious reasoning 
leads us to conclusions which are applicable to all 
kinds of ratiocination. These conclusions are: 
that the fundamental element of the mind is the 
image ; that reasoning is an organization of images, 
determined by the properties of the images them- 
selves, and that the images have merely to be 
brought together for them to become organized, 
and that reasoning follows with the inevitable 
necessity of a reflex. In order to demonstrate this 
general conclusion as clearly as possible, we shall 
systematically avoid all the side issues to which a 
subject such as this frequently gives rise. 



4 THE PSrCHOLOGT OP RBASONIAG. 

The word perception is vague enough. Medical 
men usually confound perception with sensation; 
they say of many a patient that he has lost the 
perception of red or of blue, while they are really 
speaking of the sensation of these colours. Hume 
called all states of consciousness perception. In 
modern times, certain psychologists, M. Janet 
among others, defined perception as the act by 
which the mind distinguishes and identifies sensa- 
tions. We shall adopt in this book the definition 
given by English psychologists* and we shall des- 
ignate as perception the act which takes place 
when our mind enters into relation with external 
and present objects. 

Perception is, from the common-sense point of 
view, a simple act ; it is a passive state, a kind of 
receptivity. To perceive an external object, our 
hand for example, is simply to be conscious of 
the sensations which the object produces on our 
organs. Some examples will, however, suffice to 
show that in every act of perception, the mind con- 
stantly adds to the impressions of the senses. 
Everybody knows that we can hear the words of a 
familiar song clearly, while we are frequently unable 
to distinguish those of an unknown song, even when 
both songs are sung by the same voice, a fact which 
plainly shows the share due to the mind. Instead 
of our seeking examples, proofs may be produced. 
Wundt and his pupils have made several experi- 
ments on this subject. An unknown sketch, an 
engraving, is illumined by a series of electric sparks, 

*Bain, The Emotions and The Will, p. 5S3. 



DEFINITION OF PERCEPTION. 5 

and it is noted that the perception of this sketch, 
while very much confused during the first sparks, 
becomes more and more distinct. The impression 
produced on the retina is nevertheless the same at 
each flash; but the perception becomes each time 
more complete and precise, by the help of the 
recollection formed in the mind by the preceding 
perceptions.* One might add some more examples 
drawn from the perception of space, the complex 
and secondary character of which has been known 
to us since the days of Berkeley. 

Perception is therefore a mixed state, a cerebro- 
sensory phenomenon produced by an action on the 
senses and a reaction of the brain. It may be com- 
pared to a reflex, the centrifugal period of which, 
instead of manifesting itself externally in move- 
ments, would be expended internally in awakening 
associations of ideas. The discharge follows a 
mental channel instead of a motor one. 

But psychology demands a larger measure of 
precision. It is not enough to say that in every 
perception there are sensations and something more 
which the mind adds to the sensations. What is 
the nature of this addition? This question may be 
best answered by the study of the illusions of the 
senses. It is now known that in such illusions the 
error is not to be imputed to the sensitive organ, as 
the ancients believed, but to the mind. An illusion 
is a mixed phenomenon, composed, like the sen- 
sory perception of which it is a counterfeit, by the 
co-operation of the senses and the mind. The 

*Experiments cited by M. Lachelier {Revue i>hilosoi>hique, February 
1885.) 



6 THE PSrCHOLOGT OF REASONING. 

sensory impressions are always what they ought to 
be, the nature of the external excitant and the state 
of the sensitive organ being given. The error lies 
in the co-operation of the mind, in the interpreta- 
tion of the sensations. Now, the examination of 
some illusions will be sufificient to show in what this 
co-operation of the mind consists, and what is to 
be understood by an interpretation of sensations. 

One of my friends, now a university professor, 
has related to me this story of his youth. One 
evening, when he was walking alone in a country 
broken up by large woods, he perceived, in a clear- 
ing, a large fire lighted. Then, immediately after, 
he saw an encampment of gypsies around this fire. 
There they were, with their bronzed faces, lying on 
the ground and engaged in cooking. The night 
was dark, and the place very lonely. Our young 
man was afraid, he lost his head completely, and, 
brandishing the stick he held in his hand, he dashed 
furiously into the gypsies' camp. A moment after 
he was in the middle of a pond, convulsively 
clasping a tree-trunk with his arms, and feeling the 
chill of water which rose as far as his knees. Then 
he saw a will-o'-the-wisp flickering on the surface 
of the pond ; it was this shining spot which had 
been the starting point of his sensory illusion. 

I owe the following account to another of my 
friends. Dr. G. A. One day when he was ascending 
the Rue Monsieur-le-Prince in Paris, he thought he 
read on the glass door of a restaurant the two 
words verhascum thapsus. This is the scientific 
name for one of the scrophulariacese of our country, 



DEFINITION OF PERCEPTION. 7 

which is commonly called ''bouillon blanc." My 
friend had passed the preceding days in preparing 
for an examination in natural history ; his memory 
was still surcharged with all those Latin names 
which render the study of botany so tiresome. 
Surprised at the inscription which he had just per- 
ceived, he retraced his steps in order to verify its 
accuracy, and then he saw that the tariff of the 
restaurant bore the simple word "bouillon." This 
word had suggested "bouillon blanc" to his mind, 
and this in turn had suggested verbasciim tJiapsus. 

These are two cases in point. They show us the 
composition of the element which the mind adds 
to sensation in the perception of external objects. 
This element must bear a remarkable resemblance 
to sensations, since it is indistinguishable from 
them. The young man who traverses a forest 
really believes that he sees before him a band of 
gypsies; all this phantasmagoria comes from a 
brain rendered delirious by fea. ; it is a psycholog- 
ical phenomenon which, whatever its nature, is 
very nearly related to sensation, since it does duty 
for it. Similarly Dr. A. believes he sees written on 
the door of a restaurant words which exist only 
in his mind ; for this confusion to be possible it is 
necessary once again that the mind should have the 
power of producing, of manufacturing and of objec- 
tivizing certain simulacra which in a striking manner 
resemble sensations. 

For several years past these pseudo-sensations 
have attracted the special attention of psycholo- 
gists. They are called representations in Germany, 



S THE PSrCHOLOGT OF REASONING. 

In France the prevailing term is images; it is 
this which we shall use. 

A definition of sensory perception will form the 
conclusion of this short introduction : Perception 
is the process by which the mind completes, with 
the accompaniment of images, an impression of 
the senses. 

We shall begin by studying these images. Their 
role is of the greatest importance ; in many cases 
they almost entirely efface the consciousness of the 
sensations which have given rise to them. It is this 
fact which justified Helmholtz in comparing the 
perception of external objects to an interpretation 
of signs. The sensations are the signs; our mind 
takes no more note of them than is necessary to 
learn their meaning. The perception of the exter- 
nal world is like the reading of a book; pre-occu- 
pied by the meaning, the reader forgets the written 
characters immediately after they are seen. This 
neglect of the sensations is proved by several inter- 
esting examples. We usually see trees and distant 
forests in green, with the lines of the hills in gray- 
blue; the gray-blue is to us the colour of distances. 
But if, altering the conditions of observation, we 
view the landscape from beneath our arms or be- 
tween our legs, the colours immediately lose their 
relations with the distances of the objects; they 
appear pure, with their true shades. We then 
recognize that the gray-blue of the distances is often 
a fairly deep violet, that the green of the vegetation 
shades off imperceptibly into this violet through a 



DEFINITION OF PERCEPTION. 9 

greenish blue, and so on. (Helmholtz.) The dif- 
ference arises from the fact that, under these con- 
ditions, the sensations are valued as such, and not 
as signs, which are merely important because of the 
images which they excite. 

Let us proceed to the study of these images. 



CHAPTER II. 

IMAGES. 



We do not here intend to give a complete theory 
of Images; such an attempt seems premature. The 
question is not, in several respects, mature. But we 
are obliged to devote several pages to the study of 
these interesting phenomena; for the knowledge of 
the nature of images cannot fail to throw light upon 
the problem of the mechanism of reasoning. In 
short, images, along with sensations, constitute the 
materials of all intellectual operations; memory, rea- 
soning, imagination are acts which consist, in an ulti 
mate analysis, of grouping and co-ordinating images, 
in apprehending the relations already formed be- 
tween them, and in reuniting them into new rela- 
tions. ' 'Just as the body is a polypus of cells, ' ' said 
M. Taine, "the mind is a polypus of images." 

It is not long since an apparent agreement was 
reached regarding the psychological nature of 
images. Some ancient authors, it is true, had 
already seen what has escaped a number of our con- 
temporaries. Aristotle said that one could not 
think without a sensible image. But many intelli- 
gent minds were loath to admit that material signs 
were essential to the exercise of thought. This 
seemed to them to be a concession to materialism. 



IMAGES. II 

In 1865, at the time when a great discussion on 
hallucinations was taking place among the members 
of the "Societe medico-psychologique," the phi- 
losopher Garnier and some eminent alienists, such as 
Baillarger, Sandras and others, still held that an im- 
passable chasm separates the conception of an object 
which is absent or imaginary — ^otherwise called an 
image — and the actual sensation produced by a 
present object; that the two phenomena differ not 
only in degree, but in kind, and that they resemble 
each other no more than "the body and the 
shadow." It is interesting to compare the opinion 
of these writers with the replies which Galton 
obtained previously from a large number of scientific 
men, when he began his great inquiry into Mental 
Images (Mental Imagery). He asked, in a question- 
naire which he circulated, whether one was able to 
represent absent objects mentally by a kind of 
internal vision — he took a thoroughly English ex- 
ample : the appearance of breakfast when served — 
and if this entirely subjective representation had 
common characteristics with the external vision. 
While uneducated people, women, furnished him 
with very interesting replies on the nature of mental 
vision, the scientific men to whom he appealed 
refused to believe in this faculty, which seemed to 
them to be merely a figure of speech. 

Things have changed since that time. Psy- 
chologists and physiologists — notably M. Taine and 
Mr. Galton* — have endeavored to determine the 

*Taine, On Intelligetice, Part i, book II; Galton, Inquiries into Human 
Faculty and its Development, p. 83. 



13 THE PSrCHOLOGT OF REASONING. 

nature of images, their seat in the brain, and their 
relations with sensations. They have shown that 
each image is a sensation spontaneously revived, 
generally simpler and more feeble than the original 
impression, but capable of acquiring, under given 
conditions, an intensity so great as to make us be- 
lieve that the external object is still seen. The 
complete demonstration of these truths, which now- 
adays have finally become trite, will be found in 
special works ; they are now only useful in filling 
out second-rate psychological treatises. 

We may remark in passing that this theory of 
the image is in no way materialistic ; it connects the 
image with the sensation, making the former a pre- 
served and reproduced sensation. Now, what is a 
sensation? It is not a material fact; it is a con- 
scious state, like an emotion or a desire. If one is 
tempted to see a material fact in the sensation, it is 
because it has a very apparent physiological correl- 
ative, the excitation produced by the exterior 
object upon the organ of the senses and transmitted 
to the brain. But it is known that all mental 
phenomena are accompanied by a physiological 
phenomenon. That is the law. The sensation 
and the image do not differ in this respect from 
other states of consciousness. 

The development of images is very variable. It 
varies, according to Galton, with race. The 
French, he says, appear to possess this gift, as 
attested by their talent for organizing ceremonies 
and fetes, their aptitude for strategy, and the 



IMAGES. 13 

clearness of their language ; figure s-voits is an ex- 
pression which is often met with in French. Age 
and sex appear likewise to be of importance. The 
power of visualizing is more developed among chil- 
dren than among adults, among women than among 
men. There are probably some children, says 
Galton, who pass years of difficulty in distinguishing 
between the objective and the subjective world — 
that is to say, between sensations and images. 

But it is important, first of all, to distinguish the 
different kinds of images, which are as numerous as 
the different kinds of sensations. Each sense has 
its images, these being therefore visual, auditory, 
tactile, motor, etc. We are able, when we exercise 
our memory on an object, to cumulatively employ 
every kind of image, or to have recourse to only a 
single kind. Every person has his own habits, 
depending on the nature of his organism. 

We must therefore distinguish several varieties 
of individuals, several types.* Common experience 
made this distinction long ago as far as memory is 
concerned ; it is recognized that there is often, in 
the same man, a natural inequality in the different 
forms of memory ; a certain person recollects sounds 
best of all, another colours, a third figures and dates, 
etc. Pathology has proved the independence of 
these partial memories, showing that some may 
disappear and leave the others intact. Thus it is 
that a man may lose the single memory for words, 
or forget a single language, or be deprived solely of 

*The idea of distinguishing several sensory types is due to M. Charcot, 
who has explained it in his lectures on Aphasia, at the Salpetriere. 



14 THE PSrCHOLOGT OF REASONING. 

his musical memory, etc. M. Ribot has made 
a very complete study of these partial amnesias. 

We are thus prepared to study the sensory 
types. It m.ust be understood that this inequality 
of the kinds of memory depends upon a more gen- 
eral cause, the inequality of the kinds of images; 
that those individuals who have, for example, a 
good visual memory, are those in whom visual 
images predominate; that consequently it is not 
merely the visual memory that is most conspicu- 
ous in them, it is also the visual reasoning, the 
visual imagination, etc. One may call these people 
visuels. There are thus several types, characterized 
by the predominance of one order of images in the 
mental routine. 

One of the most common types is certainly the 
indifferent type. In those who belong to this class 
no one kind of imiage is more developed than the 
others. When they wish to recall a person, they 
see in their minds the form and colour of his figure 
as clearly as they hear the sound of his voice. The 
visual memory is equal to the auditory memory; 
these two memories may besides be very well de- 
veloped, or may have remained rudimentary, but in 
every case they are of equal value. The indifferent 
also, in his reasonings, in his imaginings, in his 
dreams, employs the different kinds of images in 
equal proportions. This is perhaps the most frequent 
type ; it is the normal type, the approach to which 
must be expected, since it infers a harmonious 
development of all the sensory functions. 

Alongside the indifferent type must be placed the 



IMAGES. 15 

visual type, which is also very common. A large 
number of persons make use almost exclusively of 
visual images ; if, for example, they think of a 
friend, they see his figure, but do not hear his 
voice; when they wish to learn a page of a book 
by heart, they impress upon their memory the 
visual image of the page with its characters, and in 
reciting it by heart they have this image before 
their mind's eye, and read it. When they recall 
an air, they see distinctly, by the same process, the 
notes of the score. But it is not only their memory 
which is visual; all their other faculties are. When 
they reason, or when they exercise their imagina- 
tion, they employ visual images alone. The exclu- 
sive development of the mind in a single sense per- 
mits the visuel to perform operations which are 
feats of skill. There are chess players who, with 
their eyes shut and their head turned to the wall, 
carry on a game of chess. It is clear, says 
M. Taine, that at each move the appearance of the 
whole chess board, with the arrangement of the 
various pieces, is present to them as in an internal 
mirror; otherwise they would be unable to foresee 
the consequences of the move which has been 
made against them and the move which they wish 
to make. Two friends who possessed this faculty 
often played mental chess games together while 
walking on the quays and in the streets. Galton 
tells us that a person of his acquaintance was in the 
habit of calculating with an imaginary calculating 
rule, the several parts of which he read mentally 
according as they were necessary for each of his 



l6 THE PSTCHOLOGT OF REASONING. 

problems. Many orators have their manuscript 
placed mentally before their eyes when they speak 
in public. Certain painters, designers and sculptors, 
after they have attentively studied a model, are 
able to make a copy of it from memory. Horace 
Vernet and Gustave Dor6 possessed this faculty. 
A painter once copied from memory a Martyre de 
Saint-Pierre by Rubens with an accuracy which 
deceived the connoisseurs. An English painter, 
mentioned by Wigan, painted a portrait standing, 
after only one sitting from the model. He held 
the man in his mind, placed him mentally on the 
chair, and every time that he looked at the chair 
he saw the person seated. Little by little his mind 
became confused ; he alarmed that the model had 
actually sat, and finally he became insane. 

Such is the danger of this hypertrophy of the 
visual image. Those who possess such an intense 
visualization are half under the influence of halluci- 
nation, and it is a hundred to one that the halluci- 
nation will some day become complete. We may 
acid that very probably visiiels are specially predis- 
posed to hallucinations of the sight, and conse- 
quently to the forms of delirium of which visual 
hallucinations are the symptom. According to this 
theory, a pure visiiel can never become q. persecute, 
because in the persecution delirium only the hallu- 
cinations of hearing are, in general, according to 
Lasegue's observation, met with. The perseciitd 
does not see his persecutors, he merely affects to 
hear them. We shall see later that there is an 
objective sign whereby we may recognize whether 



IMAGES. 17 

an individual does or does not belong to the visual 
type. 

Persons who belong to the pure visual type are 
exposed, besides, to a serious danger; when they 
happen to lose, by one of those accidents which 
pathologists are at present earnestly studying, their 
faculty of mental vision, they lose everything at the 
same time. It is impossible, or at least extremely 
difficult, for them to make use of the other images, 
which have remained in a rudimentary state. The 
indifferent type is much better situated ; what is 
lost on the score of sight, for example, is regained on 
the score of hearing; substitutions are made be- 
tween the different kinds of images. 

M. Charcot has related, in one of his clinical 
lectures, an interesting pathological case, bringing 
to light the existence of the visual type and show- 
ing the kind of disorder which occurs among these 
subjects when they lose their faculty of mental 
vision. We reproduce, with a little abridgment, 
the observation published by M. Bernard {Pj-ogres 
medical, July 21, 1883). 

"M. X., a merchant at A , was born at 

Vienna; he is a very well educated man; he knows 
German, Spanish and French perfectly, as well as 
Latin and Greek classics. Until the beginning of 
the affection which brought him to Professor Char- 
cot, he read the works of Homer at sight. He 
knew the first book of the Iliad well enough not to 
hesitate in continuing a passage the first verse of 
which had been said before him. 

''His father, professor of Oriental languages at 



1 8 THE PSrCHOLOGT OF REASONING. 

L , likewise possessed one of the most remark- 



able of memories. It was the same with his 

brother, professor of law at W , with one of his 

sisters, a distinguished painter; his own son, aged 
seven years, already knows the most insignificant 
historical dates wonderfully well. 

"M. X. enjoyed until a year ago an equally 
remarkable memory. Like that of his father and of 
his son, it was principally a visual memory. His 
mental vision gave him, as soon as he wished, the 
representation of the features of persons, the form 
and the colour of things with as much distinctness 
and intensity, he asserts, as the reality itself. 

"If he were looking for a fact, a number men- 
tioned in his voluminous correspondence, which 
was written in several languages, he found them 
again immediately in the letters themselves, which 
appeared to him in their exact purport, with the 
smallest details, irregularities and erasures in their 
wording. 

"When he repeated a lesson at school, or a piece 
from a favorite author later, two or three readings 
had fixed the page in his memory with its lines and 
its letters, and he repeated it while mentally reading 
the desired passage, which, as soon as he wished, 
appeared before him with great distinctness. 

"M. X. has traveled much. He was fond of 
sketching the landscapes and views which had 
struck him. He drew fairly well. His memory 
gave him, whenever he wished, the most accurate 
panoramas. If he wished to recollect a conversa- 
tion, to bring back a speech or a spoken word, the 



IMAGES. 19 

place of the conversation, the physiognomy of the 
speaker, in a word, the whole scene, a detail of which 
was all he sought, appeared to him in its entirety. 

" M. X. 's auditory memory was always wanting, or 
at least it never appeared to be other than a second- 
ary matter with him. He has never had, among 
others, any taste for music. 

"A year and a half ago he became worried about 
some important debts the payment of which seemed 
uncertain to him. He lost his appetite and his sleep ; 
his fears were not justified by the event. But the 
emotion had been so intense that it did not subside, 
as he hoped, and one day M. X. was suddenly 
startled to find that he had considerably changed. 
At first there was complete disorder; there was 
thereafter a strong contrast between his new state 
and the old. For a while M. X. believed that he 
was threatened with insanity, so many things around 
him seemed new and strange. He had become nerv- 
ous and irritable. The visual memory of forms and 
colours had in every case, as he was not slow to per- 
ceive, completely disappeared, and this knowledge 
had the effect of reassuring him on his mental con- 
dition. He found, besides, little by little, that he 
was able, by employing other forms of memory, to 
continue to successfully direct his commercial affairs. 
He has now resigned himself to the new situation, 
the difference between which and M. X.'s original 
situation, described above, may be readily shown. 

"Every time M. X. returns to A , which he 

frequently leaves on business, it seems to him that 
he is entering" an unknown town. He looks at the 



20 THE PSrCHOLOGT OF REASONING. 

monuments, streets and houses with astonishment, 
as when he arrived there for the first time. Paris, 
which he has frequented as often, produces in him 
the same effect. Memory returns, however, httle 
by little, and at last he again discovers, readily 
enough, his route in the labyrinth of streets. When 
asked to give the description of the principal square 

in A , of its arcades, of its statues, he says: 'I 

know that that exists, but I can imagine nothing 
of it, and can tell you nothing about it.' He had 

often before drawn the roadstead of A ; now he 

vainly tries to reproduce the principal lines, which 
completely escape him. 

"His visual memory of his wife and children is 
powerless. He recognizes them at first no better 

than he does the roadstead and streets of A , 

and even by the time when, in their presence, he 
succeeds in doing so, he seems to see new traits 
and new characteristics in their physiognomy. 

''He does not go so far as to forget his own per- 
son. Recently, in a public gallery, he found him- 
self barring the passage of a person to whom he was 
about to make his apologies, and who was only his 
own image reflected by a mirror. 

''During our conversation, M. X. complained 
strongly of several returns of the visual loss of col- 
ours. He seemed more concerned about this than 
about the rest. 'My wife has black hair; I am 
perfectly sure of that. It is a complete impossibil- 
ity for me to find that colour again in my memory, as 
complete as that of imagining her person and her 
features.' 



IMAGES. 21 

"This visual amnesia also extends to the things 
of childhood as well as to more recent things. M. X. 
no longer knows anything visually of the pater- 
nal mansion. This memory was formerly very near 
to him, and he evoked it often. 

"The examination of the eye gave completely 
negative results. M. X. suffers from a myopia as 
strong as -/D. Here is also the result of the ex- 
amination of M. X.'s ocular functions made with 
the greatest care by Dr. Parinaud, in the ophthalmic 
room at the hospital: No ocular lesions or func- 
tional troubles objectively apparent, if there be not 
always a slight enfeeblement of the chromatic sensi- 
bility, affecting all colours equally. 

"We may add that no somatic symptoms pre- 
ceded, accompanied or followed this loss of the 
visual memory observed in our patient. 

"M. X. is now obliged, like almost everybody 
else, to open the copies of his letters so as to find 
the information he wants there; and he must, like 
all the world, peruse them before he comes to the 
place he is looking for. 

"He recollects no more than a few of the first 
verses of the Iliad, and in the reading of Homer, 
Virgil or Horace he no more than begins, so to 
speak, to feel his way. 

""He utters, half -aloud, the figures which he is 
adding, and he is no longer able to proceed save by 
small partial calculations. 

"When he recalls a conversation, when he 
wishes to recollect a thing said in his presence, he 
plainly feels that he must now, and not without 



22 THE PSl'CHOLOGT OF REASONING. 

effort, consult his auditory memory. The words, 
the recollected speeches., seem to hivi to resound in his 
ear, a sensation which is quite nezv to him. 

"Since this great change occurred in him M. X. 
has been obliged, in order to learn anything by 
heart, a series of phrases for example, to read these 
phrases aloud several times, and thus influence his 
ear, and later, when he repeats the thing he has 
learned he has a very clear sensation of internal 
hearing preceding the delivery of the words, a 
sensation which was previously unknown to him.* 

"An interesting detail is that, in his dreams 
M. X. no longer has, as before, the visual representa- 
tion of things. The representation of words alone 
remains to him, and these belong almost exclusively 
to the Spanish language." 

The auditory type seems to us to be rarer than 
the preceding types; it is recognized by the same 
distinctive characteristics. Persons of this type 
conceive all their recollections in the language of 
sound; in order to recall a passage they impress 
upon their minds, not the visual aspect of the page, 
but the sound of their words. Reasoning is with 
them auditory, as is memory; for example, when 
they perform a mental addition, they verbally 
repeat the names of the figures, and in some way 
add the sounds, without having a representation of 
the written sign. Their imagination also takes an 
auditory form. "When I write a scene," said 
Legouve to Scribe, "/ hear; you see; at each 

*I am now obliged, writes M. X. . . to say to myself the things which I 
■wish to retain in 7ny memory, -while formerly I had merely to ^hotogra^ih 
them by my sight. 



IMAGES. 23 

phrase which I write, the voice of the person who is 
speaking strikes my ear. You, who are the theatre 
itself,' your actors walk, act before your eyes; I am 
the listener and you the spectator.''' "Nothing 
could be more correct, ' ' said Scribe. * ' Do you know 
where I am when I write a piece? In the middle 
of the parterre." (Cited by Bernard in De 
Vaphasie, p. 50.) It is plain that the/^/r^ auditif, 
seeking to develop only one of his faculties, is capa- 
ble of accomplishing, like the visuel, regular feats 
of memory ; for example, Mozart noting down from 
memory, after two hearings, the Miserere of the 
Sixtine Chapel; deaf Beethoven composing huge 
symphonies and repeating them to himself inter- 
nally. By way of compensation, the auditif, like 
the visuel, is exposed to serious dangers ; for if he 
lose his auditory images, he is left resourceless; he 
is completely bankrupt. 

It is possible that those who are subject to hallu- 
cinations of the hearing and those individuals who 
are attacked by the delirium of persecution belong 
to the auditory type ; and that the predominance 
of one order of images creates a predisposition to a 
corresponding order of hallucinations — and perhaps 
also of delirium. 

We have yet to speak of the motor type, which 
is perhaps the most interesting of all, and by far the 
least known. People who belong to this type, the 
inoteurs, as they are called, make use of, in memory, 
reasoning and all their other intellectual operations, 
images derived from movement. To fully under- 
stand this important point, it will be sufficient to 



24 THE PSrCHOLOGT OF REASONING. 

remember that all "our perceptions, in particular 
the important ones, those of sight and touch, imply- 
as integral elements movements of the eye or the 
members; and that if movement is an essential 
element when we see an object really, it must play 
the same role when we see it ideally."* For exam- 
ple, the complex impression of a ball, which is there 
in our hand, is the resultant of optical impressions 
of the eye, impressions of touch, of muscular 
adjustments of the eye, of movements of the fingers, 
and of the muscular sensations which result there- 
from. f When we think of the ball, this idea must 
comprise the images of these muscular sensations^ 
as it comprises the images of the sensations of sight 
and of touch. Such is the motor image. That its 
existence was not earlier recognized is due to our 
knowledge of the muscular sense being compara- 
tively recent ; it was never discussed in ancient 
psychology, where the number of the senses was 
reduced to five. 

There are people who remember a drawing bet- 
ter when they have followed the outlines with their 
finger. Lecoq de Boisbaudran made use of this 
means in his teaching of art, in order to accustom 
his pupils to draw from memory ; he made them 
follow the outlines of the figures with a pencil held 
at a distance in the hand, thus obliging them to 
associate the muscular with the visual memory. 
Galton relates a curious corroborative fact: "Colo- 

*Ribot, The Diseases of the Will, p. 5. (Chicago: The Open Court 
Pub. Co.) 

tW. James has shown that these muscular sensations are the afferent 
sensations which proceed from contracted muscles, stretched ligaments, 
compressed articulations, etc. The Feeling of Ejfort, Boston, 1880. 



IMAGES. 25 

nel Moncrieff, " he says, "informs me that 
young Indians occasionally came to his quarters, 
and that he found them much interested in any 
pictures or prints that were put before them. On 
one of these occasions he saw an Indian tracing the 
outline of a print from the Illustrated News very 
carefully with the point of his knife. The reason 
that he gave for this odd manoeuvre was that he 
would remember the better how to carve it when 
he returned home."* In this case the motor 
image of the movements was intended to reinforce 
the visual image; this young savage was a niotetir. 

Should this process not be generalized and ap- 
plied to education? It is probable that a child 
would learn to read and write more quickly if he 
were trained to trace the characters at the same time 
as they were spelt. The belief that it is impossible 
to do two things well at the same time is a prejudice. 
By making reading and writing proceed together, 
the two memories, visual and motor, are constrained 
to associate and to aid one another like two horses 
harnessed to the same carriage. 

The motor image enters as an essential element 
into a large number of mental combinations, 
although its presence is often unsuspected. The 
memory of a movement is based upon motor 
images; when these images are destroyed, the 
memory of the movement is lost, and, which is 
more curious, in certain cases even the aptitude to 
execute it. Pathology supplies us with several ex- 
amples of this, in motor aphasia, in agraphia, etc. 

*Galton, Inquiries into Human Faculty and its Development, p. 106. 



26 THE PSl'CHOLOGT OF REASONING. 

Let us take the case of agraphia. An educated man, 
knowing how to write, loses all at once, suddenly, 
as a result of cerebral accidents, the faculty of writ- 
ing; his arm and his hand are in no way paralyzed, 
and yet he is unable to write. Upon what does 
this powerlessness depend? He himself says: upon 
his no longer knowing. He has forgotten how he 
must proceed in order to trace the letters, he has 
lost the memory of the movements to be executed, 
he no longer possesses the motor images which 
when formerly he set himself to write directed his 
hand. It is possible, thanks to hynotism, to vary 
the examples of these systematized paralyses, which 
affect only a particular system of movements, leav- 
ing the others intact and the arm completely free. 
It is in this way that we may make a hypnotized 
subject lose, by suggestion, the faculty of accomp- 
lishing a definite act, such as smoking, sewing, 
embroidering, laughing, etc. We have often in- 
sisted on the advantage which hypnotism offers in 
this respect, in the study of the majority of motor 
and sensitive troubles. * 

Other patients, struck by verbal blindness, make 
accurate use of these motor images in order to make 
up for what they lack in another way. We collect 
all these examples because the subject is not popular- 
ly known ; it will be useful if we combine several facts 
scattered here and there, and endeavour to make a 
synthesis of them. An individual afflicted by ver- 
bal blindness is no longer able to succeed in reading 
the characters placed before his eyes, although his 

*Binet,and Fere, Les para lysies par suggestion {Revtie scieniifique,]\x\y. 



IMAGES. 27 

vision may be intact or sufficiently good to permit 
of perusal. The loss of the faculty of reading is 
sometimes the only trouble which exists at a certain 
time ; the patient who is thus maimed may, how- 
ever, succeed in reading, but indirectly, by means 
of a roundabout method which he often discovers 
for himself; all he has to do, in order to understand 
the meaning of the characters, is to trace them with 
his finger. What happens in a case such as this? 
By what mechanism can he establish a substitution 
between the eye and the hand? The motor image 
gives us the key to the problem. That the patient 
is able to read, in some way, with his fingers, is 
because he receives, in describing the characters, a 
certain number of muscular impressions which are 
those of writing. We may say at a stretch, the 
patient reads while writing (Charcot) ; that is, the 
graphic motor image suggests the meaning of the 
characters according to the same standard as the 
visual image. 

We have just seen the place which the motor 
image occupies in the sphere of sight and in the 
sphere of movement. Its role is no less important 
in the sphere of hearing. There are persons in 
whom the mental representation of a sound is 
always a motor image of articulation. M. Strieker 
is one of the number. He it is who was the first 
to make the particulars of this subject known. The 
follov/ing are the principal proofs he has employed : 
"When I form," he says, "the image of the letter 
P, the same sensation is produced in my lips as if I 
were reallv about to articulate it. If I think of the 



28 THE PSYCHOLOGT OF REASONING. 

letter R, I experience the same sensation at the 
base of the tongue as if I expressly wished to utter 
that consonant. In my opinion, this sensation 
constitutes the essence of the image of sound." 
Such is the first proof; the second is that it is im- 
possible to imagine a letter at the same time as the 
muscles used in articulating it are given a fixed 
position which prevents them from entering into 
action. One cannot think of the letter B, which 
is a labial, while the mouth is held wide open, a 
position Avhich hinders the movement of the lips. 
Finally, the third proof is that one cannot have at 
one and the same time the representation of two 
letters, A and U for examiple, when the muscles 
which are employed in articulating them are the 
same. ''Whoever," he says, "is capable of simul- 
taneously producing, by constraining his breathing 
for a sufficient interval, the sounds A and U, is 
justified in regarding my theory as null and void. 
I need do no more than appeal to the judgment 
of the reader. Such a simultaneity is absolutely 
impossible, since the very muscles employed in the 
formation of the auditory image of A must also be 
used in forming that of U. Now, I could not 
innervate them simultaneously — as would neverthe- 
less be necessary — in one manner for the sound A 
and in another manner for the sound U." 

To make this quite clear, it must be remarked 
that M. Strieker's experiments are in no way con- 
cerned with the visual image of letters ; it is evident, 
for example, that one may graphically represent to 
one's self the letter B while the mouth is kept open; 



IMAGES. 29 

but that is not the question. M. Strieker meant, 
by the representation of a letter, tlie auditory rep- 
resentation alone, that which constitutes internal 
speech. This author maintains that what is taken 
to be an auditory image, that is to say, an enfee- 
bled repetition of the sound which is heard when a 
given letter is pronounced, has nothing to do with the 
sense of hearing; it is a motor image, a beginning of 
an articulation which stops before reaching its end. 

Objections have been raised to M. Strieker's 
work by M. Paulhan, who entirely disputes the 
facts advanced. M. Paulhan has performed all the 
experimenta cruets laid down by M. Strieker, and he 
states that he can do a large number of the things 
which M, Strieker declares to be impossible. "I 
find," he says, "that I am able, w\\i\Q pi'onotnicing 
the letter A aloud, to represent to myself mentally 
the series of vowels, and even to imagine an entire 
phrase ; I conclude from this that, since under these 
conditions — that is to say, the muscles used in pro- 
nouncing A being innervated — the motor image of 
the other vowels cannot be produced, I conclude 
from this, I say, that the image of the other vowels 
and of the other words is not, at least for me and 
those who feel like me, a motor image." 

What does this difference of opinion prove? 
Simply that the two observers have different images 
and belong to different types. M. Strieker belongs, 
for a certainty, to the motor type ; he is so to this 
degree that he does not even conceive that others 
might be constituted differently. It is by virtue of 
the exaggeration, the abnormality which the phe- 



So THE PSrCHOLOGT OF REASONING. 

nomenon presents in him, that he has discovered a 
fact which no one had noticed. But as we have 
always the defects of our quahties , M. Strieker 
completely ignores the role which sight and hearing 
play in the recollection of words, and he attributes 
everything to the motor image. He even goes as 
far as to make this astonishing observation : "I 
have not yet met any one who could have said to 
me that he imagined the contents of a newspaper 
article with the printed characters which composed 
it. One may remember several articles by heart, 
several phrases, but as words which are pronounced 
internally, and not as graphic images of words 
which might be read in the memory, as on the 
printed page." It would be difficult, one will 
admit, to write anything more false. All the 
visiLels, and they are many, do what M. Strieker 
declares to be impossible. This is a good illustra- 
tion of the remark that everybody, in philosophiz- 
ing, gives us the theory of his own nature. 

On the other hand, it is probable that M. Paul- 
han and those who feel like him belong to the 
purely auditory or the indifferent type. Such is 
the very simple solution which may reasonably be 
given to this httle debate.* 

II. 

The theory of the Image was at the point at 
which we have just left it when M. Fere and my- 
self approached the study of this phenomenon. f We 

*Stricker, Le langage et la musique, Alcan, 1885; for the discussion 
with M. Paulhan, see Revtie pkilosophique, years 1883 and 1884, j^flj^m. 

■\Thcorie des halhuinations {Revue scienii/igue, January, 1885). 



IMAGES. 31 

introduced experiments in hypnotism, which 
enabled us to settle a number of undecided ques- 
tions ; from these experiments, which we shall 
briefly recapitulate, there follows a consequence 
which is important in connection with the seat of 
images. Hitherto we have refrained from defining 
this seat ; and we might yet with advantage main- 
tain, while adhering to what has preceded, that the 
image is simply localized "in the soul" and pos- 
sesses, as has been said, a purely spiritual existence. 
But this is not the case ; there exist precise, proved 
and incontestable facts which demonstrate that the 
image — or rather the corresponding nervous process 
— has a fixed seat in the brain, that this seat is the 
same for the image and the sensation, and that, 
finally, to sum the whole matter up in a single 
formula, the image is a phenoinenon which results 
from an excitation of the sensory centres of the cor- 
tex. 

We shall therefore expound what might be called 
a physiological theory of the image, or at least, if 
the phrase is too pretentious, a series of experi- 
ments which treat of the physiology of the image. 
These experiments were made in M. Charcot's clin- 
ical laboratory at the Salpetriere, on young hys- 
terico-epileptic girls, who were completely hypnot- 
ized according to the ordinary and frequently 
described processes.* 

We know that is possible to produce hallucina- 
tions of all the senses in hypnotized subjects during 

*For further details, I refer the reader to the work which I have written 
in collaboration with Dr. Fer6: Le magnetisme animal {Bibliotheque 
scientifiqiis internationale, Alcan, Paris). 



33 THE PSrCHOLOGT OF REASONING. 

certain stages of the trance, and especially during 
somnambulism. These induced hallucinations 
form one of the most familiar psychical symptoms 
of hypnotism. The voice is generally used to pro- 
duce them. When the subject is suitably prepared, 
when the right moment has come, we have only to 
say to him, authoritatively, "There is a serpent," 
for him to see it crawling before him. This hallu- 
cination is subjective, personal to the subject, and 
consequently may be easily feigned ; but it presents 
so many objective characters that its existence can- 
not be doubted, at least in the cases in which these 
characters are present. Therefore we shall not stop 
to discuss the hypothesis of simulation again; in 
proportion as we proceed with our exposition, the 
reality of the phenomenon will be proved. 

How can the experimenter excite hallucinations 
by speech? How can he make the subject come 
to see a serpent or a bird merely by what he says to 
him? Can this phenomenon be explained? And is 
there any analogous phenomenon in the normal life 
of a wide-awake individual? Such are the questions 
which a psychologist should, in view of these expe- 
rimental hallucinations, put to himself. We raise 
these questions because, while investigating them, 
we shall show how experiments in hallucination 
may be useful to the theory of Images. 

When, during a conversation with a wide-awake 
person, we speak to him of the colour red, and he 
understands the meaning of that word, we raise zxy 
image in his mind, the image of red, by virtue of 
the association which has been established by educa- 



IMAGES. 33 

tion between the word and the idea; but this 
created image is generally very feeble, very pale ; 
after being barely caught sight of, it vanishes, like 
a "super" who has merely crossed the stage. The 
word has excited in the wide-awake person a vision 
of red, but a short, rapid and defective vision. Dif- 
ferent circumstances may render the vision more 
durable and more powerful, even during the waking 
state. Here is a striking example of this. It is 
related that on the evening of the execution of 
Marshal Ney, several people were assembled in a 
Bonapartist room; suddenly the door opened and 
the servant, mistaking the name of one of the 
arrivals, who was called M. Mar^chal Ain6, an- 
nounced aloud: "Monsieur le Marechal Ney.-' 
At these words a thrill of fear ran through the 
gathering, and those who were present have since 
related that for an instant they distinctly saw in 
M. Marechal, Ney himself advancing in person into 
the middle of the room. Here we touch upon the 
suggested hallucination, if the phenomenon does not 
actually belong to that class. The hallucinations 
which are produced in the hypnotic state by the 
voice of the experimenter do not possess a different 
mechanism. The voice of the experimenter excites 
the auditory centre of his subject, and this centre, 
once awakened, transmits its excitation to the visual 
centre, by virtue of pre-established dynamical asso- 
ciations. Then the visual image arises and ob- 
trudes itself with so much the more energy that it 
reigns alone in the consciousness of the patient ; the 
part of his brain which is excited is the only part 



34 THE PSrCHOLOGT OF REASONING. 

which reacts, and it consequently gives its maxi- 
mum. But let us put aside these particular condi- 
tions which make the image evoked so intense and 
transform it into a hallucination. What is import- 
ant for us to show is the fact that the phenomenon 
of suggested hallucination in hypnotism is not iso- 
lated from ordinary intellectual processes ; that, on 
the contrary, its germ exists in the images which 
people our mind during the waking state, and that 
hallucination may definitely be made use of as an 
exaggeration of the image in studying its properties. 
The first fact to v/hich we shall call attention, 
from the point of view of the physiology of the 
image, is the effect of achromatopsia or color blind- 
ness. It is known that a large number of hysterical 
subjects display an insensibility which extends over 
one entire half of the body and divides it vertically 
into two parts; this hemi-anaesthesia is usually 
accompanied by more or less pronounced sensory 
anaesthesias ; on the insensible side the hearing is 
enfeebled, the nostril smells odours with difficulty, 
and one-half of the tongue cannot distinguish the 
tastes of the foods which are placed upon it. But 
what really interests us most is the state of the eye. 
This organ shares with the others in the insensibil- 
ity. In most cases a concentric contraction of the 
visual field is observed, and at the same time the 
loss or enfeeblement of one or several sensations of 
colour, in other words, achromatopsia. This loss of 
colours occurs according to a definite order. The 
colour which is first lost is violet; green is second; 
this order is constant in all patients. In the case 



IMAGES. 35 

of the other colours, two classes, which occur almost 
equally often, must be laid down; in the one, the 
patients lose violet, green, red, yellow and blue 
successively; in the other, the red and blue are 
inverted, and the series reappears thus: violet, 
green, blue, yellow and red. 

It is interesting to investigate the influence 
which achromatopsia might exercise upon coloured 
hallucinations which are suggested during hypnot- 
ism. M. Richer was the first to observe that if 
only the achromatoptic eye of a hypnotized subject 
is kept open, it is impossible to suggest any coloured 
hallucinations to her by the medium of that eye. 
If the patient have lost the colour violet, it is impos- 
sible to make violet enter into her hallucinations, 
and so on. Here are some examples of this: 

''^ Bar, in the waking state, is achromatoptic in 
her right eye. Keeping her left eye closed, we 
make her see a flock of birds. To our questions on 
the colour of their plumage, she replies that they are 
all white or gray. If we insist, assuring her that 
she is mistaken, she maintains that she sees only 
white or gray birds. But the state of affairs alters 
if at that moment we open her left eye, whether 
her right eye be closed or not ; she is immediately 
enraptured with the variety and brilliance of their 
plumage, in which all the different colours are com- 
bined. 

"This experiment has been varied in many 
ways. Closing her left eye we show her Harlequin, 
and she describes him as all covered with gray, 
white or black squares. Polichinelle is likewise 



36 THE PSrCHOLOGT OF REASONING. 

dressed in white or gray. "It is original, ' ' she says, 
"but it is not pretty." Immediately upon open- 
ing her left eye the notion of colour reappears, and 
Harlequin and Polichinelle appear to her in motley, 
as they are commonly represented."* 

The same rule appears to extend, as I have 
shown, to the spontaneous hallucinations of insan- 
ity. I have observed a hysterical lunatic, who was 
a patient of Dr. Magnan's at the Asile Sainte- 
Anne, continually possessed with the image of a 
man dressed in red. This woman was hemi-anaes- 
thetic and achromatoptic in the left eye; when her 
right eye was closed she continued to perceive her 
hallucination with her left eye, but the man who 
appeared to her was no longer red ; he was gray, 
and seemed as if surrounded by a mist. 

Thus blindness in one colour obstructs the hallu- 
cination — that is to say, the image of that same 
colour. How may this be explained? Very simply, 
if we consider achromatopsia as a cerebral phenom- 
enon, as a functional disturbance of the cells of the 
cortex affected by the sensation of colours. Since 
this functional disturbance places the same obstacle 
in the way of the hallucination as in that of the 
sensation of a given colour, it seems probable that 
the sensation and the image employ the same kind 
of nervous elements. In other words, the halluci- 
nation would take place in the centres where sense 
impressions are received ; it would result from an 
excitation of the sensory centres. What is said of 
the hallucination applies directly to the image. 

*P. Richer, Etudes cUniqites siir riiysteroepilepsie, p. 708, and. edit. 



IMAGES. 37 

It will perhaps be objected that there are some 
hypnotized hysterical subjects in whom achroma- 
topsia does not prevent the suggestion of coloured 
hallucinations. But it seems to us to be easy to 
explain this departure from the rule. We shall 
confine ourselves to remarking that achromatopsia in 
hysterical subjects depends upon hemi-ansesthesia; 
that this loss has nothing definite about it ; that it 
is less a paralysis than a paresia, an inactivity of the 
nervous elements. These elements no longer 
respond to the call of their normal stimulus, col- 
oured light ; but there is nothing astonishing in their 
reacting when they are attacked from another side, 
by an excitation which comes from the auditory 
centres and is nothing else than verbal suggestion. 
Other facts may be given to corroborate the 
localization of the image in the sensory centre. A 
large number of observations collected by M. 
Fere show that a constant connection exists be- 
tween the special sensibility of the eye and the gen- 
eral sensibility of its integuments. When a cereb- 
ral lesion causes sensitive disturbances in the 
integuments of the eye, visual disturbances, such as 
achromatopsia and concentric or lateral shrinking of 
the visual field are, on looking a little closely into 
the matter, likewise met with. In hysterical hemi- 
anaesthesia, a connection is also observed between 
the sensibility of the conjunctiva and of the cornea 
and the special sensibility of the organ ; these two 
sensibilities are always affected to a similar degree. 
The interpretation of these and many other facts 
too numerous to be repeated here, has led M. Fere 



38 THE PSrCHOLOGr OF REASONING. 

to the following conclusion : that there exist in 
undetermined regions of the encephalon sensitive 
centres which are common to the organs of the 
senses and to the integuments which surround 
them.* 

Now, if we carefully examine all that happens 
when a visual hallucination is produced in a hyp- 
notized subject, we see that in many cases the hal- 
lucination modifies the sensibility of the external 
membranes of the eye. In the cataleptic state, the 
conjunctiva and the cornea, outside the pupillary 
field, are generally insensible ; but as soon as the 

visual hallucination has been produced, in P 

for example, the sensibility of the external mem- 
branes returns to the condition in which it exists 
during the waking state; the membranes cannot be 
touched by a foreign body without exciting palpe- 
bral reflexes, t With the said M the hallucina- 
tion continues for several minutes on awakening, 
always producing a dysaesthesia of the membranes 
of the eye, which lasts exactly as long as the hallu- 
cination. With the said Wit , the unilateral 

hallucination produces a slight pain in the eye 
which is alone hallucinated; "I feel as if there were 
sand in that eye," says the patient. These three 
observations seem to show that the visual hallu- 
cination, or, in a more general way, the visual 
image, implicates the centre of vision. 

But we have not yet approached the most inter- 

*Ch. F^re, Troubles fonctionnels de la vision, pp. 149, 150 and 151. 

tCh. Fere, Les hysteriques hypnotiques coninte sujets (T experimenta- 
tion, etc. {Arch, de neurologie, 1883, t. VI, p. 122). 



IMAGES. 39 

esting observations in this class of ideas. We have 
yet to speak of the chromatic phenomena produced 
by hallucinations of the sight. 

Let us first of all recall three physiological 
experiments v/hich may easily be performed with- 
out much apparatus. In the first experiment we 
take a card divided into two equal parts, the one 
red, the other white, and having at its centre a 
point for the purposo of fixing the sight ; if we gaze 
at this point for several moments, we see a green 
colour appearing on the white half. This is the 
chromatic contrast.* In the second experiment we 
gaze fixedly upon a little red cross with a black spot 
at its centre ; if we then turn our eyes to a sheet of 
white paper bearing a black spot, we immediately 
see a green cross appearing. This is the negative 
consecutive sensation. In the third experiment we 
take two cards, one red and the other green, and 
place them on a table, one a short distance before 
the other; then, with a sheet of glass held before 
the eye, we look at one of the cards through the 
transparency and at the same time try to obtain the 
reflected image of the other card in order to carry it 
on to the first ; as soon as the images of the two 
cards are superposed, their colours blend, and we 
obtain a resultant colour which is generally grayish 
(the exact tint depends upon the colour of the cards, 

*Without wishing to raise any complicated physiological problems here, 
we may recall the fact that a general agreement does not exist upon the ex- 
planation of simultaneous contrast and consecutive images. Helmholtz 
attributes the effects of the simultaneous contrast to an error of judgment; as 
for consecutive sensations, he localizes them in the retina, and explains them 
by Youno-'s theory and that of Fechner. For our part, we entirely share Dr. 
Parinaud's opinion, which assigns a cerebral seat to those two phenomena, 
and attributes to them as their sole cause a material modification of the 
nervous centres. {Soc. de BioL, May 13 and July 22, 1882), 



40 THE PSTCHOLOGT OF REASONING. 

the intensity of the light, etc.). This is the blend- 
ing of complementary colours. 

We may repeat these three experiments with 
cards coloured by suggestion, that is to say with 
hallucinations of colour. If, as M. Parinaud has 
shown, we produce in a patient the hallucination 
of red on one-half of the white sheet, she sees green 
appearing on the other half. If, as we have ob- 
served along with Dr. Fere, we make a red cross 
appear on a white sheet, the patient, after having 
contemplated this imaginary cross for several mo- 
ments, sees upon another sheet of paper a green 
cross. Finally, if we teach her to superpose, 
according to the process described, cards coloured 
green and red by suggestion, the patient sees 
the resultant gray tint, which is produced by the 
blending of these two complementary colours. 

In view of these results, is it possible to doubt 
that visual hallucination results from an excitation 
of the sensory centre of vision? If it were other- 
wise, how could we understand that hallucination 
should give rise to the same chromatic effects as 
sensation? 

We may transfer all these phenomena revealed 
by the study of visual hallucination to the visual 
image itself. This extension of experience is so 
much the more legitimate since Wundt has shown 
that the simple image of a colour, contemplated for 
a long time in the imagination, gives rise to the 
consecutive sensation of a complementary colour. 
If we, in our minds, gaze fixedly for some moments 
at the image of red, we perceive, on opening our 



IMAGES. 41 

eyes upon a white surface, a green tint.* It is 
difficult to repeat this experiment, for it demands 
a power of visuaHzation which everybody does not 
possess. To take myself as an example, I cannot 
imagine a colour clearly; I am a visucl of a very 
mediocre type. Therefore it is not astonishing 
that I fail to obtain a consecutive coloured sensation. 
But my excellent friend, Dr. Fere, easily succeeds in 
doing this. He can imagine a red cross so vividly 
as to see afterwards, on a sheet of paper, a green 
cross; thus he sees not only the colour, but the 
form.f 

These facts show the strict analogy existing be- 
tween the sensation, the hallucination and the 
image ; we may conclude from this that whether 
we have the sensation of red, whether we have the 
recollection of red, or whether we see red in a hal- 
lucination, it is always the same cell which vibrates, ij; 

So far we have been content to assert that the 
image has the same seat as the sensation, without 
seeking to determine anatomically what that seat 
is. The preceding experiments do not enable us to 
solve this last question, which is much more com- 
plicated and difficult than the first. We might here 
introduce the principal results of the study of cereb- 
ral localization, which seem to show that the sen- 
sory centres are situated at the level of the cerebral 
surface-layers, in a zone still ill-defined, probably 

*Cited by Bain in the Appendix to The Senses and the hitelleci. 

jTliis experiment affords an objective sign which allows us to recognize 
whether a person belongs to the visual type. 

tAll the preceding experiments have treated of the visual image. The 
reader will judge to what extent it is legitimate to extend the conclusion 
derived from them to the images of the other senses. 



42 THE PSyCHOLOGT OF EEASONTNG. 

situated behind the motor zone. But we prefer to 
confine ourselves to the basis of hypnotic experi- 
mentation, from which we may still learn some- 
thing upon this subject. It is a primary fact in 
the study of hypnotic hallucinations that these 
sensory troubles, when they have a unilateral form, 
are transferable by the magnet.* This transfer is 
accompanied by a certain number of objective signs 
which exclude all idea of simulation ; thus the 
shifting of the phenomenon is followed, in certain 
subjects, by a shifting in the inverse direction, then 
by several other shiftings, phenomena which have 
been described in connection with the transfer of 
anaesthesia by the name of consecutive oscillations; 
further, according as the transfer is effected, the 
patient complains of pains in the head, which oscil- 
late from one side of the head to the other; these 
characteristic pains, which we have proposed to call 
transfer pains, are not diffuse ; they have a fixed 
seat, and that a most remarkable one. In the case 
of hallucinations of the sight, the pain in the head 
corresponds to the anterior part of the inferior 
parietal lobule, as M. Fere's researchesf in cranio- 
cerebral topography have enabled us to ascertain ; 
in the case of auditory hallucinations, the painful 
spot corresponds to the anterior part of the sphe- 
noidal lobe. These two localizations are in perfect 
asfreement with the results of clinico-anatomical 
reseaches; they therefore deserve to be taken into 

*Binet and Fere, Le transfert ^isyschique {Revue philosophique, 
January, 1885). 

tCh. Fere, Note sur quelqiies points de la to-pogra-pliie die cerveau 
{Arch, de phys. norm, et path., 1876, p. 247); Nouvelles Recherches sur la 
topographie cranio-cercbral {Revue d\T,iithrop.., 1881, p. 46S). 



IMAGES. 43 

serious consideration. The centre of visual sensa- 
tions has been placed in the inferior parietal lobule, 
and the auditory centre in the sphenoidal lobe. It 
therefore seems permissible to consider that visual 
images and auditory images very probably result 
from the excitation of these two centres. 

We finally reach the same conclusion as Herbert 
Spencer and Bain, but with the advantage of pred- 
icating proofs at our disposal for what these 
authors considered as merely probable: "The 
renewed feeling, ' ' said Bain, ' ' occupies the very same 
parts and in the same manner as the original feel- 
ing." 

III. 

We have not yet finished our short study of 
Images. After having determined their seat in the 
brain, we shall proceed to indicate their principal 
physiological properties. 

Mr. Spencer calls images faint states, in oppo- 
sition to sensations, which are vivid states. The 
term is correct. The lack of vividness of images is 
one of the reasons which prevent them from being 
conveniently observed and which explains why their 
nature has so long been unrecognized. In order 
to study them it is necessary to compare them with 
consecutive images of sight, ^ phenomena which follow 
the impression of an exterior object on the retina. 

We know that consecutive images are of two 
kinds, positive and negative. Place a small red 
square upon a brightly lighted white surface ; look 
at this square for a second, then shut your eyes 



44 THE PSrCHOLOGT OF REASONING. 

without strain, by covering them with your hand, 
and you see the red square appearing; this is the 
positive image. Repeat the same experiment by 
gazing for a long time at the red square, then, on 
closing the eyes or fixing them on a different point 
on the white surface, you will see this same square 
appearing, but instead of being red it will be green, 
the complementary tint ; this is the negative image. 

The consecutive image constitutes a transition 
type between the sensation and the ordinary image ; 
it is like the sensation inasmuch as it immediately 
follows the action of a ray of light upon the retina, 
and it is like the image inasmuch as it survives that 
action. The consecutive image is generally fairly 
intense ; it may be experimented upon with more 
result than the ordinary image. 

M. Parinaud has demonstrated the cerebral seat 
of the consecutive image by the following experi- 
ment {Soc. de Biol,, 13th May, 1882): 

"M. B^clard relates as follows, in his treatise on 
physiology, an experiment which is little known : 
'The impression of a colour upon the retina awakens 
on the same point on the other retina the impres- 
sion of the complementary colour. Example : Shut 
one eye, gaze for a long time with the open eye at 
a red circle ; then shut this eye, open the one which 
was shut, and you will see a green aureole appear- 
ing.' (Edition dated 1866, p. 863.) 

"Thus presented, this experiment is open to criti- 
cism ; its very formula enunciates an error; but, re- 
stored to its true meaning, it contains the demonstra- 
tion of the proposition which I have just put forward. 



IMAGES. 45 

"In order to give a proper account of the nature 
of the sensation developed in the eye which has not 
received the impression, let us first of all see what 
takes place in the eye which receives the impres- 
sion. 

"Shutting the left eye, for the moment excluded 
from the experiment, we gaze at a red circle on a 
sheet of white paper, or better, at a point marked 
at the centre of the circle, in order to fix the eye 
better. After some seconds the white background 
loses its intensity and the colour itself becomes dim. 
Drawing the circle away without taking our gaze 
off the point, we see appearing on the paper the 
image of the circle coloured green and brighter than 
the background ; this is the negative image. Shut 
the eye, and the image, after having disappeared 
for an instant, is reproduced with the same charac- 
teristics. 

"Let us now repeat Beclard's experiment — that 
is to say, at the moment when we draw away the 
circle, let us shut the impressed right eye and open 
the left eye, gazing always at the paper. 

"The image of the circle does not appear im- 
mediately. 

"The white of the background darkens at first, 
and it is only then that the image takes form, col- 
oured in green and brighter than the background. 
It is the same negative image, exteriorized by the 
left eye, as we recognized in the right eye which 
received the impression.* 

*M. Giraud-Teulon, who has repeated the experiment, attributes the 
same characters to it (Unpublished note sent to M. Charcot). 



46 



THE PSTCHOLOGT OF REASONING. 



"We may produce the same transfer with the 
positive image by varying the conditions of the 
experiment. 

"The exteriorization of the adventitious image 
by the eye which has not received the impression 
necessarily implies the intervention of the brain 
and, in all probability, the cerebral seat of the 
image itself."* 

This experiment on the consecutive image seems 
to me to be very important for our theory; I have 
repeated it a very large number of times. In the 
course of these studies I have noticed some curious 
phenomena. First of all, the experiment may be 
made with both eyes open. We gaze at a red cross 
with the right eye, keeping the left eye open, but 
preventing this eye from seeing the cross by inter- 
posing a screen. At the end of some seconds we 
shut the right eye; and shortly after the left eye, 

*M. Parinaud adduces a second proof, which seems to us much less satis- 
factory. He remarks that the consecutive image follows the intentional 
movements of the eye, but is not displaced when the optical axis is deviated 
by the finger. Now, a retinal image, he says, would be displaced in the 
mechanical deviation of the ball, as well as in its intentional movements. 
The conclusion does not seem to us to be just. It is readily admitted in 
psychology that we perceive the movements of bodies by the eye in tv>'o ways: 
ist, when the eye is steady and the image of the object changes its place on 
the retina; 2nd., when the eye is in movement and the image of the object 
does not change its place on the retina. This last case is that in which we 
follow a moving object with our eyes, for example a rocket rising in the air. 
It has moreover been remarked that the state of repose or movement of the 
eye translates itself into consciousness by the absence or the presence of the 
sensations which accompany the contractions of the ocular muscles; that is 
that our consciousness takes account solely of intentional movements. These 
two rules explain the majority of optical illusions relating to movement. 
Thus the consecutive images appear to move with the gaze, for in this case 
we experience muscular sensations which are the sign of the movement of the 
eye, and, in addition, the consecutive image is not displaced on the retina. 
When the eye is mechanically deviated, we have no muscular sensations, the 
eye seems steady; consequently, on the one hand the exterior objects, which 
are really steady, appear to move, for their image is displaced on our retina, 
considered as fixed, and on the other hand the consecutive images appear 
steady, for their image does not change its place at all on our retina, con- 
sidered as fixed. In short, eveiry object which appears to move with the 
movements of the eye ought to appear steady when the eye is mechanically 
deviated, and vice versa. These are the results of our psychical education. 
No argument, either for or against the retinal seat of the consecutive image 
can be drawn therefrom. 



IMAGES. 47 

which has remained constantly open, sees the point 
on the paper at which it gazes become covered with 
a faint shadow, and at the middle of this darkened 
surface appears a green cross. 

We must also note the changes which take place 
when seeing the transferred consecutive image ; it 
appears, as M. Parinaud has very fitly remarked, 
after a certain delay; it never lasts very long, at 
least with my eyes ; it usually disappears at the end 
of two seconds, and the paper resumes its original 
white tint at the same time. But this is not all, 
and if we keep our eye fixed on the same point we 
see the paper, some seconds after, darken once 
more and the image reappear with the same charac- 
teristics of form and colour as it had at first. The 
number of these oscillations seems to depend on the 
intensity of the image; I have often counted three 
of them. 

I have also found that the other eye, the one 
which has gazed steadily at the red cross, preserves 
its consecutive image during all this time, and that 
we can, by opening and shutting our two eyes 
alternately, see the direct consecutive image and 
the transferred consecutive image succeed each 
other. 

This succession of the two images allows us to 
compare them. They do not always have the same 
characteristics; I have found that there is a fairly 
decided difference of tint for certain colours. For 
example, an orange-coloured wafer gives me a con- 
secutive image which is almost blue when seen 
directly, and almost green when it is transferred ; 



48 THE PST'CIIOLOGT OF REASONING. 

this difference is maintained no matter which eye is 
used at the beginning of the experiment. The two 
images present practically the same tint for other 
colours. 

Another proof of the cerebral seat of the con- 
secutive image is that it sometimes appears long 
after the impression and in this case it resembles an 
ordinary recollection. Newton, by an effort of 
attention, was able to reproduce a consecutive 
image, produced by gazing steadily at the sun sev- 
eral weeks previously. It is well known, says M. 
Baillarger, that persons who are in the habit of 
using the microscope sometimes find objects which 
they have been examining for a long time reappear 
spontaneously some hours after they have left their 
work. M. Baillarger,* having worked some hours 
daily for several days at preparing specimens of 
brains with fine gauze, saw all at once gauze contin- 
ually covering the objects in front of him, 
and this hallucination was repeated for some days. 
This is an analogous case to that of M. Pouchet, 
who saw {Societe de Biologic, 29th April, 1882), 
while walking in Paris, the images of his microscopic 
preparations superposing themselves on exterior 
objects. This phenomenon is not rare; numerous 
examples are to be found for the seeking. This 
reviviscence of the long-expired consecutive image, 
a long time after the excitative sensation has ceased 
to act, completely excludes the idea that the con- 
secutive image is preserved in the retina ; the preser- 
vation is made in the brain, and, very probably, 

*Quoted by Taine, On Intelligence, p. 53. 



IMAGES. 49 

when the image reappears, it does not involve the 
cones and rods of the retina in fresh activity. 

We may therefore admit, as a very probable fact, 
that the consecutive image has a cerebral seat. 
This conclusion is interesting for the psychologist ; 
because it leads him to establish a parallel between 
the consecutive image and the image of memory. 
In what do they differ? First of all, in intensity; 
the consecutive image is so vivid that it may be 
projected upon a screen and fixed there by draw- 
ing. Are there many recollections which could be 
exteriorized in the same fashion? Then, by the 
mode of appeai'ance; most frequently the consecu- 
tive image immediately follows a visual sensation, 
sometimes it appears spontaneously much later, and 
it is never excited by a psychical cause, by associa- 
tion of ideas, as are the ordinary images of memory. 
Observers have been struck with this fact. M. 
Pouchet has remarked that at the moment when 
the image of his microscopic preparations rose be- 
fore his eyes, he was in a cab, chatting with a per- 
son who knew nothing of science, and he has been 
unable to perceive the slightest connection between 
this image and the subject of his conversation. 

The comparison of the consecutive image with 
the image of memory is of considerable interest ; for 
experiment shows that the consecutive image pos- 
sesses a certain number of attributes, which further 
belong also to the image of memory. Thus: First, 
it changes its place with intentional movements of 
the eye and movements of the head when the look 
is fixed ; second, it becomes larger when the screen 



50 THE PSTCHOLOGT OF REASONING. 

on which it is projected is drawn away, and shrinks 
when the screen is brought nearer; third, it is dis- 
torted with the inclination of the screen and it 
lengthens in the direction of the inclination. 

A real image, painted on the screen, behaves 
quite otherwise. If the screen be drawn away 
from the eye, this image becomes smaller; if the 
screen be brought nearer, the image becomes larger; 
if the screen be inclined, the image is distorted and 
shrinks in the direction of the inclination. This 
is what painters call foresJiortening.'^ In short, the 
consecutive image and the real image (the sensa- 
tion) present inverse properties up to a certain 
point. What is the reason of this? The question 
may be readily answered. 

Let us first of all suppose, for greater clearness, 
that the consecutive image has its seat in the retina, 
with the reservation of modifying our demonstration 
afterwards to make it agree with the theory of the 
cerebral seat. We must depart from the principle, 
so firmly established by Helmholtz, that every sub- 
jective sensation is perceived, exteriorized and 
localized in the same fashion as if it corresponded 
to an exterior object. Let the consecutive image 
be A' B', on the retina; if it be projected outside, 
on a screen held at E F, it will have the dimension 
of the line A B, because that would be the dimen- 
sion of an object which, placed at the distance of 
the screen, would make on the retina an image 

*It is only after a little exercise that one can succeed in giving an 
account of these changes in the dimensions of the image, because, as they do 
not correspond to any change in real dimensions, we have contracted the 
habit of correcting them. 



IMAGES. 



51 



equal to A' B' ; in fact, the two lines A' C and B' 
C are carried from the two extremities of the image 
to the optical centre of the eye and produced until 
they meet the line A B. Now let us alter the dis- 
tance of the screen, and what happens? As the 
subjective image is of constant size on the retina, it 
must assume on the screen the dimension of an 
object which, situated at the new distance where 
the screen is placed, would make on the retina an 
image equal to A' B'. Therefore we have only to 
calculate the successive sizes of an object subject to 
this condition of always producing at the back of 
the eye a retinal image of the same size, in spite of 
its changes of distance. 

In order to simplify the problem, we shall give 
the consecutive image the form of a circle; there- 
fore, we may replace the visual angle A C B by a 
right circular cone, with its vertex at C, and A C 
and B C as its generating lines. This granted, 
when the consecutive image is projected on a screen, 



E 




the screen cuts this cone, and the size and form of 
the conic section are those of the object which, at 
the distance at which the screen is held, produces 
a retinal image equal to A' B' ; consequently they 



52 THE PSrCHOLOGY OF REASONING. 

are also those of the projected consecutive image. 
Thus, when the screen is held vertically (that is to 
say, perpendicular to the optical axis), the consecu- 
tive image must have a circular form, because the 
section is made in a plane perpendicular to the axis 
of the cone and is of circular form ; when the screen 
is inclined, the consecutive image must lengthen, 
because the section is oblique and of elliptical form; 
when the screen is drawn away, the image must 
become larger, because the section is made further 
from the vertex of the cone and becomes larger. 
This is confirmed by experiment. 

That this is not so for the real image, painted 
upon the screen, is because its apparent diameter 
augments when the object is brought nearer, dimin- 
ishes when it is drawn away, and diminishes in the 
direction of the inclination when it is inclined. 
We shall not dwell upon this point. 

One may perhaps be tempted to conclude from 
this demonstration that the consecutive image 
really has its seat in the retina, for it would not 
behave otherwise if it were retinal. But it is to be 
remarked that the transferred consecutive image 
possesses the same properties. We have several 
times stated that it enlarges and contracts when 
the screen is drawn away and brought nearer. 
Will it be maintained that this transferred image is 
retinal? Received by the right eye, it is exterior- 
ized by the left eye, which has remained closed 
until the last moment ; it is therefore very probable 
that it has not impressed the left retina. 

*'It is rational to admit," says M. Richer on 



IMAGES. 53 

this subject, "that the retina has an exact represen- 
tation of itself in the cerebral visual centre. There 
exists a sort of cerebral retina each point of which is 
in intimate connection with corresponding points 
of the peripheral retina."* Therefore it is under- 
stood that an impression conveyed directly to a 
point of this cerebral retina (the consecutive image) 
produces the same effect on consciousness as an im- 
pression which would lie on the corresponding point 
of the peripheral retina, to right or to left, either 
above or below, or on the yellow spot. 

We willingly admit, until we have proof to the 
contrary, that the properties of the consecutive 
image are common to the ordinary image, to recol- 
lection for example, although they could not be 
observed in an image so feeble. But there are 
cases where the image, evoked by a person of 
healthy mind, attains a degree of intensity suffi- 
cient to exteriorize it. Brierre de Boismont, who 
endeavoured to impress upon his mind the figure of 
one of his friends, a clergyman, had acquired the 
faculty of evoking it whether his eyes were open 
or shut ; the image appeared to him to be exterior, 
situated in the direction of the line of sight ; it was 
coloured, its outlines were fixed and endowed with 
all the characteristics belonging to the real person. 
We earnestly invite those who possess the gift of 
visualizing to try the following experiment : Think 
of a red cross, project it on a screen and see if it 
behaves like a consecutive image, if it enlarges 
when the screen is brought nearer and contracts 

^Etudes cliniques sur I 'kystero-epilefsie, 2nd editiofc, 1S85, p. 714. 



54 THE PSrCHOLOGT OF REASONING. 

when it is drawn away. The success of this experi- 
ment would give a decisive confirmation to our 
thesis. 

Such are the positive characteristics of consecu- 
tive images, and probably of all images. They 
have also a certain number of equally important 
negative characteristics, which serve, as much and 
more than the first, to distinguish them from sensa- 
tions. 

We know that our sensations are directly modi- 
fied in consequence of the movements which we 
make; the aspect of my home is modified when I 
shut or when I open my eyes, when I come nearer 
it or go further away, when I press my eyes so as 
to see double, or when I interpose a prism so as to 
see it deviated, or when I reflect it in a mirror so as 
to have a symmetrical figure of it, or when I look 
at it through an opera-glass so as to have an en- 
larged view of it. . . . It is clear that none of 
these experiments has any influence on a mental 
image. When I think of an absent friend, and the 
visual image of his countenance is about to rise in 
answer to my thought, I might try in vain to 
modify the perspective of this image by changing 
my position, or to double it by pressing my eye. 
The attempt equally fails in the case of the con- 
secutive image. M. Parinaud has made an experi- 
ment in order to show conclusively that a consecu- 
tive image cannot be deviated by looking at it 
through a prism. We select the following passage 
from a manuscript note which he has been good 
enough to send us: 



IMAGES. 55 

''Gaze steadily," he says, ''with one eye at a 
thin strip of red paper on a white background ; after 
a minute, sHp between the strip and the eye a prism 
with 1 5 degrees of an angle at its larger base, keep- 
ing the gaze fixed, without trying to follow the dis- 
placement of the strip. You then see the green 
consecutive image detach itself from the upper part 
of the red strip. In order to make sure that it is 
only the image of the paper that is displaced, and 
that the consecutive image has not undergone devi- 
ation in the inverse direction, recommence the 
experiment by covering only a part of the red strip 
with the prism ; the consecutive image, if the eye 
does not change its place, protracts exactly that 
part of the strip which has not undergone the 
prismatic refraction." 

To sum up, sensations and images form two 
groups of phenomena which are distinguished by 
definite characteristics, positive and negative 
equally. 



CHAPTER III. 

REASONING IN PERCEPTION. 



In external perception the images which arise in us 
from contact with objects derive a group of proper- 
ties from their origin which are entirely wanting 
in isolated images, which we studied in the preced- 
ing chapter. Directly suggested by exterior im- 
pressions, they associate themselves organically 
with these impressions, so as to form an indivisible 
whole which corresponds to the idea of a single 
object. By means of this sensory bond each image 
consequently undergoes all the modifications which 
the sensation directly experiences. Practically, as 
regards the observer, it behaves like a true sensa- 
tion. 

The chapter which follows might therefore be 
entitled : ' ' TJic properties of images zvJdcJi are asso- 
ciated zvitJi sensations. 

In the study of these phenomena we shall turn 
once more to hypnotic hallucinations, for in the 
normal state they are too weak to be observed. 
But here a preliminary objection arises: How can 
the hallucination be of use in the study of normal 
perception, an operation which is produced by a 
cooperation of the senses and the mind? Is the 
hallucination not a sort of delirious conception 

56 



REASONING IN PERCEPTION. 57 

which arises wholly from a diseased brain ? When 
we say to a hypnotized subject: There is a serpent! 
and when, looking at the ground, she sees the 
serpent crawling towards her, what is real, what is 
objective in this apparition? Such is the objection 
which may be made a priori. But by carefully 
observing the hypnotic hallucination (the only one 
we shall refer to), and also by replacing mere 
observation by experiment, we find that a part of 
sensation enters, if not always, at least often, into 
this phenomenon. This is perhaps not an absolute 
rule, but the case is very common. 

Here is a first experiment which proves this: 
We present a pure white sheet of paper to the sub- 
ject and say to him: ''See, here is your portrait." 
The subject immediately sees his portrait appearing 
on the white surface, he describes the pose and the 
costume, adding to the suggested hallucination 
with his own imagination, and if the subject be a 
woman, she is usually dissatisfied, finding the por- 
trait little flattered. One of them, who was pretty 
enough, but whose complexion was covered with 
little freckles, said to me one day when looking at 
her imaginary portrait : "I have a great many 
freckles, but I have not so many of them as that." 
When the subject has contemplated the white card 
for some time, we take this card and shuffle it 
amongst a dozen cards of the same kind ; there are 
now thirteen similar cards, and we would be unable 
to recognize the one which carried the hallucination 
if we did not take care to mark it after having 
taken it from the hands of the patient. But the 



58 THE PSrCHOLOGT OF REASONING. 

patient has no need of marks; if we offer her the 
bundle of cards, telling her to look for her portrait, 
she recognizes the first card, usually without mak- 
ing a mistake ; better still, she always holds it out 
in the same way, and if we reverse the card accord- 
ing to its edges, she sees the imaginary portrait 
upside down. But there is something still more 
cogent. If we photograph the white card and show 
the photographic proof to the patient ten days, 
twenty days or a month after, she will still recog- 
nize her portrait on it.* 

The most simple way of explaining this local- 
ization of the imaginary portrait is to suppose that 
the hallucinatory image is associated — in an uncon- 
scious manner — with the visual impression of the 
white card ; so that every time this visual impres- 
sion is renewed it suggests the image by association. 
There are always some special details on a paper 
card, however white it may be ; we are able to find 
them with a little attention ; the patient perceives 
them instantaneously by means of her hyperaes- 
thetic visual sense; these details serve her as the 
point of identification on which to project the 
image. They are, as it were, the nails which fix 
the imaginary portrait on the white surface. This 
is so true that the portrait experiment is more 
surely successful when ordinary paper rather than 
Bristol board is used. In a general way the more 
visible the point of identification, the more durable 
is the hallucination. 

*Clearly the experiment does not succeed every time, but one success is 
sufficient, under conditions which exclude fraud, to give us the right to take 
it into account. 



REASONING IN PERCEPTION. 59 

We owe to M. Londe, the chemist of the Sal- 
petriere, the following corroborative fact : Wit — , 
being in a state of somnambulism, he shows her the 
engraving of a photograph representing a view of 
the Pyrenees, with some asses climbing a hill ; at 
the same time he says to her, "See, this is your 
portrait; you are quite nude." When she awoke, 
the patient chanced to perceive the engraving, and 
furious at seeing herself represented in a state too 
near that of nature, she jumped up and destroyed 
it. But two photographic proofs, which were care- 
fully preserved, had already been taken from this 
engraving. Every time the patient sees them she 
stamps with anger, for there she always sees herself 
represented as nude. At the end of a year the hal- 
lucination still remains. 

This exceptionally long survival of the hallu- 
cination is clearly explained by the point of identi- 
fication theory. In reality the photograph presents 
to the patient an immense number of points of 
identification, which, being associated with the 
hallucinatory image, evoke it by accumulating their 
effects with an irresistible force.* The most curious 
thing about this observation is that the patient 
does not see these points of identification, or rather 
does not take account of their nature, for it is very 
essential that she should see them so as to project 
her hallucination ; but she does not succeed in 
recognizing that they form, by their union, a view 
of the Pyrenees. It is useless to endeavour to lead 

*It has been long remarked that one recollection is much more surely 
recalled than another, when it has a larger number of lines of association at 
its disposal. 



6o THE PSrCHOLOGl' OF EBASOlYING. 

her from her error; her portrait is all she sees on 
the photograph. 

These few examples will be sufficient to show 
that hypnotic hallucination may, like perception, 
contain two elements: an impression of the senses 
and an exteriorized cerebral image. Perception, 
said Taine, is a true hallucination.* 

It is true that the mode of formation is not the 
same in both cases. The hypnotic hallucination is 
formed by an image suggested by speech, which is 
associated with a point of identification, while in 
perception the image is directly suggested by an 
impression of the senses. But between these two 
acts lies a third, which forms a transition between 
them, the illusion of the senses. The hypnotic 
illusion of the senses differs in one point only from 
the hypnotic hallucination, in that it consists of the 
transformation of an exterior object, while the hal- 
lucination creates an entirely imaginary object. 
Say to a subject, while showing him a hat : There is 
a cat, or a bird, or a house; and you produce a 
hypnotic illusion. Pronounce the same words 
without showing any object, and you suggest a hal- 
lucination. But the existence of that object which 
serves as substratum for the hypnotic illusion does 
not appear to have any importance, since it may be 
transformed in a hundred ways. The ordinary error 
of the senses, a trouble so frequent that everybody 
knows it by experience, takes its place alongside the 
hypnotic error of the senses. Who has not heard 
a burglar's step in the creaking of a piece of furni- 

tA. Binet, L ^Hallucination {Revue philosophique, April and May, 
18S4). 



REASONING IN PERCEPTION. 6 1 

ture; who has not seen a human figure in the con- 
fused forms of a landscape by night? These illu- 
sions are distinguished from those of hypnotism by 
their mode of formation. In the hypnotic state the 
image which transforms the object is suggested by 
speech, it comes from within ; in the normal state 
the false image is suggested by a defective vision of 
the object, it comes from without. But apart from 
this difference, the two are alike. In short, the 
illusion of the senses is intimately connected with 
exterior perception, which it in a manner counter- 
feits. Consequently perception and hallucination 
are bound together by an uninterrupted series of 
intermediate states. Thus we are permitted to 
consider the ordinary illusion of the senses, the 
hypnotic hallucination, and finally the hallucination, 
as more and more accentuated distortions of per- 
ception. This proved, we proceed to utilize these 
facts of the morbid state in the study of the normal 
state. 

Brewster was the first to observe that if the eye 
of a person in the state of hallucination be pressed, 
the imaginary object is seen double. The fact has 
been confirmed by observations made by Paterson, 
Despine and Ball. This last named doctor has 
reported the most curious example. It concerned 
a hysterical young girl who, in the crises of natural 
somnambulism, saw the Holy Virgin appearing to 
her in a resplendent costume. This miraculous 
apparition was invariably doubled by ocular pres- 
sure; two Virgins appeared before her. M. Fer6 
has in his turn found that by operating on hys- 



62 THE PSrCHOLOGT OF REASONING. 

terical subjects who can be hypnotized it is possible 
to repeat this curious experiment as often as desired. 

How shall this Jialhicinatory diplopia be ex- 
plained? It is clear that we are unable to double a 
mental image directly by pressing on the eye. If 
I think of an absent friend, I shall never succeed in 
seeing him double by pressing on my eye. If, 
therefore, the visual hallucination may be divided 
under these circumstances, that indicates that it is 
not ''altogether image"; in reality it is associated 
with an impression of the senses — that is to say, 
with an exterior point of departure; the ocular 
pressure doubles this point, and the cerebral image 
shares this doubling consecutively by a sort of re- 
bound. 

Now, this is precisely what occurs in visual per- 
ception. When we look at an object while touch- 
ing or pressing on our eye to make it deviate from 
its normal position, we see the object double; the 
object, we say. Now, what is an object? A group 
of sensations and images; the images are therefore 
doubled, like the sensations; the sensory diplopia 
is therefore accompanied by a mental diplopia. 
But the fact is not readily apparent. It would not 
be noticed, save for the hallucination, which hyper- 
trophies it, rendering the image enormous and 
reducing the sensation to almost nothing. In this 
way pathological facts instruct us regarding the 
normal state. We learn here that in our percep- 
tions the image is so firmly bound to the sensation 
that it indirectly undergoes its modification ; it is 
doubled when the sensation is doubled. 



REASONING IN PERCEPTION. 63 

M. Fere has replaced ocular pressure by a prism. 
Placing a prism before the eye of a patient in the 
state of hallucination, he found that the hallucina- 
tion was doubled as before, and that, further, one 
of the images underwent a deviation whose direc- 
tion and value were according to the laws of optics. 
It will be fully understood that the experiment was 
made when all exterior objects whose modifications 
might serve as marks were removed from the visual 
field of the patient. For example, the patient is 
inculcated with the idea that a profile portrait is on 
a neighbouring table. If, without forewarning, a 
prism be interposed before one of her eyes, the 
patient is astonished to see two portraits, and the 
one which is deviated is always placed according to 
the laws of optics. (Ch. Fere, Soc. Biol., 29th 
Oct., 1 88 1.) This second experiment, like the 
first, instructs us regarding the history of our nor- 
mal perceptions ; for normally, when we place a 
prism before one of our eyes, the objects which we 
see through the prism appear to us deviated. Now, 
this deviation of the objects implies a deviation of 
the images; the prism, under certain conditions, 
deviates an image. Thus we find, in the centre of 
the normal life, the germ of this curious experiment 
in hypnotism. 

We have ourselves contributed to the develop- 
ment of these studies by replacing the prism by a 
large number of other optical instruments. The 
principle being settled, the experiments offer 
scarcely any interest save that of curiosity. We 
shall confine ourselves to mentioning a few, refer- 



y^ 



64 THE PSrCHOLOGT OF REASONING. 

ring for details to our articles on hallucinations. 
If, while the patient is contemplating the suggested 
imaginary object, for example a tree on which a 
bird is sitting, we place an opera-glass before her 
eyes, she immediately declares that the tree is be- 
coming very large and is drawing nearer. If, revers- 
ing the opera-glass, we make the patient look 
through the objective glass (the large end), the tree 
suddenly recedes, shrinks, and the bird becomes 
completely invisible. The interest of this experi- 
ment lies in the remarks with which the patient, in 
the state of somnambulism, accompanies these 
changes in the imaginary object. The said Wit — 
experiences a most lively astonishment every time. 
When I make her look at a bird perched on the 
branch of a tree, she does not in the least under- 
stand how this bird can be quite near to her one 
moment and far distant the next. I tell her sev- 
eral times that the bird changes its position, that it 
flies nearer and then goes away. But she rejects this 
explanation entirely, with the objection that the 
tree also appears to occupy different positions. I 
reply that it is impossible, that the tree has its 
roots buried in the ground and cannot leave the 
place where it is planted. Then she concludes that 
her eyes are out of 'order, and that it is they which 
change the apparent distance of the objects. This 
conclusion is really a very reasonable one, it being 
stated that the patient does not know that the eye- 
piece and the objective of an opera-glass are placed 
alternately before her eyes. 

It is important to notice that the hallucination 



REASONING IN PERCEPTION. 65 

is modified only when the opera-glass has been 
adjusted to the sight of the patient. Why? Be- 
cause it is only then that the opera-glass modifies 
her visual sensation ; it enlarges the surface of the 
extej-ior body to which the image is applied, thus 
enlarging the image, which acts like a drawing on 
an india-rubber film. 

This experiment, like the preceding ones, ex- 
plains the normal state. Without dwelling on the 
matter, let us merely remember that in approaching 
a person our visual sensations are gradually modi- 
fied ; at the same time the images produced by 
these sensations are modified in the same way. If 
we are at first very far away, we see a black spot of 
unrecognizable character; then this spot becomes 
an object longer than it is broad, then we distin- 
guish a person, then we know it to be a man, then 
a man of such and such a kind, and finally we 
recognize a certain man. The images change in 
proportion as the sensations are modified by our 
approach; they become more abundant, more defi- 
nite, and they finally permit an act of individual 
recognition. Hallucination renders this phenome- 
non of the induction of sensations into images very 
apparent. 

In other experiments we have replaced the 
opera-glass with a lens, which enlarges an imaginary 
portrait and at a certain distance reverses it, by a 
bifracting crystal v/hich produces a special and 
somewhat complicated doubling, and finally by a 
microscope, which produces a much greater enlarge- 
ment than the lens. But in these different cases it 



66 THE PSrCHOLOGT OF REASONING. 

is always a matter of the same phenomenon of 
refraction, and when we know one of them we are 
able to understand them all. 

We shall describe, in conclusion, the mirror ex- 
periment. If we produce a hallucination on a fixed 
point, such as the hallucination of a cat on a neigh- 
bouring table, it is possible to get this imaginary- 
object reflected in a plane mirror, provided that 
this mirror reflects the point on the table where 
the imaginary animal is seated. The patient conse- 
quently sees two cats; both of them are imaginary, 
but it may be said that the reflected one is still 
more imaginary than the other. In fact, if the 
patient is directed to seize these animals, she readily 
catches the one on the table, but when she wishes 
to seize the reflected one her hand encounters the 
front of the mirror, which prevents it from going 
further. Moreover, observing things more closely, 
it is noticed that the mirror gives a syninietrical 
image of the imaginary object, as if it were a real 
object. It is in this way that an imaginary in- 
scription on a sheet of paper is seen reversed 
in the mirror. All these results are explained 
by the existence of the reflected point of identifi- 
cation. 

Here we have a case which clearly establishes 
the transition between hallucination and perception. 
It is an example of an illusion of the senses, which 
happened to be reflected by a mirror. One of my 
friends has related to me that, starting one night 
out of his sleep, he saw a human form before his 
window, which was faintly lighted ; shortly after, he 



REASONING IN PERCEPTION. 67 

recognized that this apparition represented the Vir- 
gin; she was standing, stretching out her open 
hands, and from each finger proceeded a ray of fire. 
At the side of the window there was a cupboard 
with looking-glasses ; the Virgin was reflected in the 
looking-glass like a real object ; the second image 
was absolutely similar to the first; the attitude was 
the same, the open hands were surrounded by the 
same luminous aureole. My friend, who is not in 
the least superstitious, did not allow himself to be 
deceived by this apparent miracle. On approaching 
the window he found that the illusion arose from a 
white cloth hung on the fastening. As was to be 
expected, the image of the cloth was reflected by 
the looking-glass. 

Although this phenomenon may appear too 
natural to deserve mention, we mention it because 
it shows that one and the same rule extends to 
hallucination, illusion of the senses and to percep- 
tion. These comparisons are exceptionally instruct- 
ive in the study of perception. 

We now understand that when we see a real 
object reflected in a mirror there happens some- 
thing which is analogous to the reflection of a hal- 
lucination and of an illusion. The mirror, consid- 
ered from the point of view of perception, is a sort 
of repeater; it repeats the visual sensations which 
the object produces on us directly. These repeated 
sensations give rise, as if they were direct sensa- 
tions, to an interpretation, to the construction of 
an exterior object by the mind — that is to say, 
definitively, to a suggestion of images. We may 



6S THE PSrCHOLOGT OF REASONING. 

therefore say that in the normal state a mental 
image is reflected in a mirror when it is connected 
with a sensation. 

We refer the reader who may desire further 
details regarding these phenomena of optical hallu- 
cination to the monograph on hallucination pre- 
pared by us in collaboration with M. Fer6. The 
aim which we pursue here is not to study hallucina- 
tion, but to explain exterior perception by hallu- 
cination, which is a very different thing. 

II. 

Hypnotic experiments on visual hallucinations 
have enabled us to penetrate in part into the mech- 
anism of our normal perceptions. The principal 
conclusion which is drawn from them is as follows: 
When an exterior object conveys an impression to 
our senses, the mind adds, upon its own initiative, 
a certain number of images to the sensations expe- 
rienced. These images, which complete the knowl- 
edge of the exterior and present object, do not 
remain inert and immobile in the presence of the 
sensations, like two bodies which have no chemical 
affinity for each other, or like two algebraic quanti- 
ties which are simply connected by the sign -{-. It 
is more than a juxtaposition. In reality a combi- 
nation of sensations and images is formed, and 
although these two elements come from very differ- 
ent sources, since one is sensory and the other 
ideal, they unite so as to form a single whole. 
This is proved by the fact that every time the 



REASONING IN PERCEPTION. 69 

group of sensations is modified, a corresponding 
modification in the group of images follows. If 
the sensation be deviated by a prism, the image is 
deviated ; if the sensation be enlarged by an opera- 
glass, the image is enlarged; if the sensation be du- 
plicated by a mirror and made symmetrical, the 
image is reflected and becomes symmetrical. This 
resonance on the part of the image is a phenomenon 
which occurs every day, every hour and every instant 
in our sensory perceptions — that is to say, quite close 
at hand. If we do not notice it, it is because it is 
too delicate, too slight. To render it more appar- 
ent we must have recourse to the hallucination, 
which magnifies it. 

In common with many authors, we shall apply 
the name percept to the product of perception — 
that is to say, the images of the exterior object 
which are definitely due to and bound to the excita- 
tive sensation. 

We have yet to study the bond which unites the 
sensation to the image. The preceding experi- 
ments have proved its existence without making its 
nature known. 

We may consider external perception as a syn- 
tJietic operation, since it results in the uniting of 
the information actually furnished by the senses to 
the information furnished by preceding experiences. 
Perception is a combination of the present with the 
past. To perceive a body which is actually in the 
field of vision, to recognize in it a certain form, 
size, position in space, certain qualities, etc., is to 
unite in a single act of consciousness actual elements 



70 THE PSrCHOLOGT OF REASONING. 

— that is to say, the optical sensations of the eye — • 
and past elements — that is to say, a crowd of 
images; it is to make a single body out of these 
unconnected elements. This is a phenomenon 
which completely escapes consciousness; by con- 
sulting that witness alone, the operation of perceiv- 
ing an object appears to be an easy and natural act 
which demands no effort of reflection on our part; 
that is in reality an illusion. Experiment and 
reasoning prove to us that in all perception there is 
work. 

But the amount of work is not constant ; it is 
clear that it varies according to circumstances. It 
would be wrong to think that there is only a single 
kind of perception. Perception is a form of activity 
which has a very variable nature, for by one of its 
extreme limits it encloses conscious reasoning, com- 
posed of three verbal propositions, and at the other 
end it becomes identified with the most elementary 
and automatic acts, such as reflexes. The amount 
of work expended in perception increases in an 
ascending series and even becomes very consider- 
able when we approach reasonings in which a sen- 
sible amount of reflexion and comparison occurs ; 
inversely, the work decreases when we descend 
towards reflex actions, without, however, vanish- 
ing altogether. It is therefore important to give 
some examples of the different kinds of perception. 
Let us begin with the lowest forms. 

"First of all,"* says Mr. Sully, in describing 
the degrees of visual perception, ''comes the con- 

*James Sully, Illusions, p. 23. 



BEASON/NG IN PERCEPTION. 7 1 

struction of a material object of a particular figure 
and size, and at a particular distance — that is to 
say, the recognition of a tangible thing having 
certain simple space-properties, and holding a 
certain relation to other objects, and more especially 
our own body, in space. This is the bare percep- 
tion of an object, which always takes place even in 
the case of perfectly new objects, provided they are 
seen with any degree of distinctness. . . . This 
part of the process of filling in, which is the most 
instantaneous, automatic and unconscious, may be 
supposed to answer to the most constant and there- 
fore the most deeply organized connections of ex- 
perience. 

"The second step in this process of presenta- 
tive construction is the recognition of an object as 
one of a class of things^ — for example, oranges, hav- 
ing certain special qualities, as a particular taste. In 
this step the connections of experience are less 
deeply organized, and so we are able to some ex- 
tent, by reflection, to recognize it as a kind of intel- 
lectual working up of the materials supplied us by 
the past. 

"A still less automatic step in the process of 
visual recognition is that of identifying individual 
objects, as Westminster Abbey, or a friend, John 
Smith. The amount of experience that is here re- 
produced may be very large, as in the case of recog- 
nizing a person with whom we have had a long and 
intimate acquaintance. . . . It is further to 
be observed that in these last stages of perception 
we approach the boundary line between perception 



73 THE PSrCHOLOGT OF REASONING. 

and inference. To recognize an object as one of a 
class is often a matter of conscious reflection and 
judgment, even when the class is constituted by- 
obvious material qualities which the senses may be 
supposed to apprehend immediately. Still more 
clearly does perception pass into inference when 
the class is constituted by less obvious qualities, 
which require a careful and prolonged process of 
recollection, discrimination and comparison for their 
recognition. . . . To say where the line should 
be drawn here between perception and observation 
on the one hand, and inference on the other, is 
clearly impossible." 

We may add that perception, in the highest 
steps of its development, assumes a particular char- 
acter. In rudimentary perception the mind simply 
infers from the sensations which it receives by one 
of its organs (for example, the eye) that the object 
has yet other properties which the other senses 
would perceive if it were necessary and if we wished 
it; thus when we look at a red-hot bar of iron, the 
red colour revives in us the idea of heat, which we 
might directly experience by bringing our hand 
near to the bar. Such a perception amounts to a 
substitution of sight for touch. 

But it is quite otherwise with the more complex 
perceptions which belong to reasoning properly so 
called. When we recognize that a plant belongs to 
the soap-worts or the lilacs by the inspection of a 
single leaf, when we discover the horn of a young 
stag, the claw of a wild boar or a wolf, on the 
mould of a forest track, the sensation received by 



REASONING IN PERCEPTION. 73 

our eye evokes the image of objects which we can- 
not at the moment see. These operations are, 
however, always of the same kind, images suggested 
by an actual sensation, and there is no reason to 
believe that the mechanism of this suggestion is 
different in the two cases. 

To sum up, we may reduce all perceptive acts 
to two types: specific recognition and individual 
recognition. It would be interesting to know if 
individual perception begins by being generic, and 
only gradually attains, by a regular progression, to 
its complete development. According to this 
hypothesis, when we see a person whom we know, we 
perceive him at first as a solid body, then as a man, 
and finally as such and such a person. This pro- 
gressive development exists; it is not only prob- 
able, it is real. This is proved by the following 
experiments in hypnotism. 

Among the effects which suggestion is capable 
of producing in a hypnotized person systematized 
ancEsthesia is certainly one of the most interesting. 
This operation consists in rendering a person or an 
object invisible to the subject; it is, properly speak- 
ing, the isolated suppression of a particular percep- 
tion.* 

We still remember the effects which the first 
experiment in anesthesia had on one of our sub- 
jects, the said W . We made this experiment 

along Avith M. Fere. W being in the trance, 

we suggested to her that she would not see M. Fere 

*Binet and Fere, Le transfert {Revtie fihiLosoihique, January, 1SS5). 
An analysis of these experiments has been published by M. Richer {oj>. cii., 
p. 724 et seq.). 



74 THE PSrCIIOLOGT OF REASONING. 

when she awoke, but that she would be able to hear 
his voice. Upon her awakening, M. Fere places him- 
self before her; she does not look at him; he holds 
his hand out to her, but she makes no gesture. 
She remains quietly seated in the arm-chair where 
she had just awakened; we are seated on a chair by 
her side. After some time she expresses astonish- 
ment at not seeing M. Fere, who was then in the 
laboratory, and asks us what has become of him. 
We reply: "He has gone out; you may return to 
your ward." M. Fere then stands before the door. 
The patient rises, bids us good-day and proceeds 
towards the door. Just as she is going to put her 
hand on the knob she strikes against the invisible 
body of M. Fere. This unexpected shock makes 
her tremble; she makes a fresh attempt to go on, 
but meeting the same inexplicable resistance, she 
begins to be frightened and refuses to renew the 
attempt. 

We seize a hat which is lying on the table and 
show it to the patient. She sees it perfectly Vv^ell, 
and assures herself, with her eyes as well as v/ith 
her hands, that it is a real body. Then we place 
it on M. Fere's head. The hat appears to the 
patient as if it were suspended in the air. Words 
could not express her astonishment ; but her sur- 
prise reaches its climax when M. Fer6 lifts the hat 
from his head and salutes her several times; she 
sees the hat, which is sustained by nothing, de- 
scribe a curve in the air. At this sight she declares 
that "this is no miracle," and supposes that this 
hat is suspended by a thread. Thereupon she gets 



REASONING IN PERCEPTION. 75 

on a chair to try and touch this thread, but she 
does not succeed in finding it. Tlien we take a 
cloak and hand it to M, Fere, who puts it on. The 
patient, who continues to gaze at this cloak with 
a look of amazement, sees it move in the air and 
take the form of an individual. "It is," she says, 
"like an empty manikin." As we speak the furni- 
ture moves and rolls noisily from one end of the 
room to the other (it is only the invisible M. Fere 
who is displacing it); the tables and the chairs are 
overturned, then order succeeds to chaos. The 
things are put back in their places, the de-articulated 
bones of a skull, scattered on the floor, are brought 
together and fitted again ; a purse opens of itself, 
and the gold and silver pieces tumble out of it and in 
again. 

This experiment on the invisibility of M. Fere 
had been made on the 20th of May, 1884. At 
the end of the proceedings we omitted to render 
M. Fere visible, which could have been done by 
hypnotizing the patient again and assuring her 
authoritatively several times that she could see 
M. Fere. On the 23d of May M. Fere was still invis- 
ible. We wished to bring this phenomenon of 
anaesthesia to an end by a new suggestion ; then we 
observed a very remarkable thing. 

It was first of all found, to the surprise of every- 
body, that the patient not only ceased to see 
M. Fere, but had lost all recollection of him, although 
she had known him about ten years. She remem- 
bered neither his name nor his existence. After 
having put her in the trance we had considerable 



76 THE PSrCHOLOGT OF REASONING. 

trouble in making M. Fere visible to her eyes; 
once awakened, she at last saw his person again, 
but, curiously enough, she did not recognize him, 
and took him for a stranger. It was most comical 
to see her get angry when M. Fere thee-and-thou'd 
her when speaking to her. Some days after, the 
patient had in the ward one of the bad attacks of 
hystero-epilepsy to which she is unfortunately 
subject. This attack completely swept away the 
last traces of the ansesthesia, and consequently the 
patient recognized M. Fere at last, without suspect- 
ing that during four or five days she had taken him 
for a stranger who was visiting the staff. 

We find in this last experiment,* which in a 
manner happened by itself — these are the best — an 
interesting application of the law of retrogression, 
the importance of which, in the destructions and 
reconstructions of the memory, has been shown by 
M. Ribot. It is really a general pathological law. 
Systematized anaesthesia consists, from the psycho- 
logical point of view, in the paralysis of an individ- 
ual perception. Here we see the anaesthesia disap- 
pear little by little, by degrees, sufficiently slowly 
to allow us to perceive its progress. The patient, 
who had at first lost the perception of M. Fere 
completely, begins, under the influence of a curative 
suggestion, by perceiving his person without recog- 
nizing it. The generic perception has reappeared ; 
the individual perception, which is more complex, 
is still paralyzed ; she sees a man without knowing 

*We mention only one experiment, but it is not unique. It appears to 
be the rule that systematic anajsthesia disappears in the manner indicated. 



HEASONING IN PERCEPTION. 77 

who he is. Then the attack comes, one of those 
great internal catastrophies which clear away the 
accumulation of a toxic substance. Then the individ- 
ual perception reappears, and recognition takes place. 

This revival of the perception, which is recon- 
structed bit by bit, following the order from simple 
to complex, from the general to the individual, 
demonstrates the hypothesis which we have ad- 
vanced ; the different orders of perception which are 
distinguished by the names of generic, specific and 
individual perception, are only the more or less 
advanced steps of one and the same process. A 
perfect continuity exists between the simplest per- 
ceptions, as for example, the perception of a colour, 
and the complicated perceptions which verge upon 
logical and conscious reasoning; and in short a sin- 
gle act, in developing, in evolving, begins by being 
a simple perception and is transformed by degrees 
into a complex reasoning. 

A comparison will bring this idea into a graphic 
form. The point of departure of every perception 
is an impression of the senses; this initial element 
is like a nucleus around which layers of images are 
concentrically arranged. But these layers are not 
identical ; the images which the sensation suggests 
first, and which form the innermost and firmest 
layer, represent the physical properties of the ob- 
ject, form, size, physical consistence, weight, etc., 
and its simplest specific properties. The proof of 
this lies in the fact that these properties are the 
first to be perceived when systematized anaesthesia 
begins to disappear. On the contrary, the images 



78 THE PSrCHOLOGT OF REASONING. 

representing the individual characteristics of the 
object constitute the most superficial and conse- 
quently the most unstable layer. Formed last of 
all, they are the first to disappear under the influ- 
ence of an inhibitory suggestion. 

We have hitherto considered only a single aspect 
of the percept, describing it as a synthesis of sensa- 
tions and images. From the logical point of view, 
the percept is a judgment, an act which determines 
a relation between two facts, or in other words, an 
act which affirms something of something. We 
content ourselves with reproducing an example 
cited by M. Paulhan in a little book which is worth 
more than many more voluminous works. 

"I have a book before my eyes, and I affirm 
that it is yellow. If we analyze this judgment, we 
find that what I affirm is the co-existence of a real 
sensation (the colour yellow) with other sensations 
which I have or can have (the white colour of the 
edges of the book, the black colour of the printed 
letters, sensations of resistance, of weight, etc.). 
But what is the nature of the act by which I believe 
these different sensations are united together? There 
is nothing in the mind save the cohesion of these 
different sensations. . . . Judgment therefore 
becomes reduced to an association of images, for 
the time being indissoluble; it is often accompanied 
by an affirmation expressed by words thought, 
pronounced or written (a verbal proposition), but it 
may exist independently of all expression ; it may 
consist solely of images."* 

*F, Paulhan, La physiologic de Vesprit^ p. 73. 



REASONING IN PERCEPTION. 79 

This is the first time we have had to speak of 
the logical value of an association of images. This 
question has been treated at length by contempo- 
rary English psychologists; we can only refer to 
their works, where one will find it established that 
the aim of all judgment is to affirm a relation of 
resemblance, co-existence or of sequence between 
two things;* that this affirmation, this belief, this 
judgment, are the external effects of an internal 
fact, the association of images present to our 
minds ;f and that, finally, as a general conclusion, 
every time that two images are closely associated, 
as for example, the image of a stone thrown in the 
air and the image of its fall, or even indissolubly 
associated like the image of a thing possessing 
resistance and the image of a thing possessing ex- 
tension, we believe that the things thus bound 
together in our mind are bound together in the same 
fashion in reality.:]: This amounts to saying that 
we exteriorize an association of images as we exte- 
riorize an image. 

III. 

We have just seen that the percept is a compli- 
cated structure, made up of sensations and images, 
and evidently formed of several layers. We are 
already a long way from the common opinion, 
according to which the function of the mind which 
perceives an object is that of the sensitive plate of a 

*J. S. Mill, Logic, pp. 71 and 73. 

fH. Spencer, Princi:ples of Psychology, Vol. 11, p. 426. 

%]. S. Mill, Examination of Sir ]A^illiani Hamilton' s Philosophy. 



So THE PSrCHOLOGT OF REASONING. 

photographic apparatus; in proportion as we get still 
nearer to the heart of our subject, we shall be more 
and more convinced of the insufificiency of that com- 
parison. 

We have several times, in alluding to the psy- 
chological nature of perception, seen in it the result 
of unconscious reasoning. Although this point is 
generally admitted by contemporary psychologists, 
save for some variations and some minor reserva- 
tions, it forms too important a part of our subject 
to allow us to accept it without discussion and 
without proof. This is a question which deserves 
to be attacked directly. 

Before discussing a problem, its terms must be 
very accurately stated. We do not intend to com- 
pare perception with formal reasoning in all par- 
ticulars. It is plain, if the proposition be under- 
stood in that sense, that what we are maintaining 
becomes a paradox. It is paradoxical to maintain 
that the act of recognizing an object by sight or 
touch resembles a syllogism. Therefore we do not 
go so far as that ; and the reason why we dwell 
upon this matter is in order to beg our critics not to 
attack us by trying to refute what we have never 
said. What we do say, what we believe to be 
true, and what we shall proceed to demonstrate, is 
that in formal reasoning there are essential charac- 
teristics which we again find in external perception ; 
that these two acts, so dissimilar in appearance, 
have yet the same internal structure, the same 
ossature. To employ a comparison drawn from 
natural history, external perception is an act of 



REASONING IN PERCEPTION. 8 1 

reasoning in the same way as the amphioxus, which 
has no vertebrae, is a vertebrate. 

To demonstrate this proposition, we may take 
at hazard an example of external perception and 
an example of formal reasoning, and compare the 
two. Let us compare the perception of an orange 
with the familiar syllogism of the schools: All men 
are mortal; Socrates is a man, Socrates is mortal. 

When we look at an orange we experience a cer- 
tain number of impressions. There is at first a 
visual impression of colour, of lights and shades, 
formed really by a very complex aggregate of sim- 
ple sensations. The muscular apparatus of the 
eye, awakened by the excitation of the retina, 
becomes the seat of contractions which are accom- 
panied by definite muscular sensations; the contrac- 
tion of the pupillary opening, the convergence of 
the axes of the two eyes, the contraction of the 
muscle of focal adaptation, the movements of the 
eyes in their sockets, etc., must be noted; there 
are also the movements of the head, neck and trunk, 
which are unconsciously performed so as to allow 
the luminous rays to reach the surface of the retina 
and the most sensitive part of that surface — that is 
to say, the yellow spot. These are almost all the 
real sensations which we receive from the object or 
in connection with the object; everything else 
about it is indirectly known, in the state of images. 

Thus the direction and the distance of the object 
— that is to say, its position in space — and its size, 
are three important facts furnished, not by the 
senses, but by the mind. This is not all. We 



82 THE PSrCHOLOGT OF REASONING. 

believe we see — that is to say, we see by the mind's 
eye — the spherical form of the orange, its glossy 
and dotted surface, the juice which it contains, the 
complicated arrangement of its internal parts, the 
presence of seeds, and at the same time zve believe 
we feel its weight, its slightly elastic consistence, 
its odour, its taste, and we believe zue hear its name 
pronounced. 

If we continue to look at the orange, we induce 
the revival of images relating to its practical utility, 
to the act of cutting it with a knife, of carrying it 
to the mouth, of sucking it and throwing away the 
pulp and the pips. 

In short, there is an immense number of images 
which cannot even be mentioned because they are 
personal to each observer, and dependent upon his 
past experience and his scientific education. All 
these images are revived, to whatever degree, by the 
presence of the object, and gravitate around that sim- 
ple impression of a yellow spot, received by the eye. 

In a subject whose actions have been rendered 
entirely automatic, this suggestion of images by an 
exterior object is so powerful that it translates 
itself outwardly in a series of acts. We give an 

umbrella to Wit , when she is in a state of 

somnambulism; she takes it, and she immediately 
shivers as if she felt the approach of the storm ; 
then she opens it and begins to walk in the labora- 
tory, tucking up her skirt and looking at her feet; 
from time to time she jumps a streamlet. The 
scene is an exceedingly curious one.* 

*For other examples see Richer, op. cit., p, 692 et seq. 



REASONING IN PERCEPTION. S3 

If we now compare the perception of an orange 
with an act of formal reasoning having as its 
object the death of Socrates, what analogy will be 
discovered? 

First. — It is hardly necessary to remark that 
these two acts belong to indirect and secondary 
knowledge. When we assert the future death of 
a living person, basing our assertion on the death 
of other men, our assertion anticipates the course of 
events; it is a prevision. In the same way, when 
we look at an orange and afhrm, explicitly or im- 
plicitly, it does not matter much, that "this is an 
orange," we pass beyond, by a mental act, the 
limit of our actual experience. This is precisely 
what the preceding analysis aimed at showing. 
The characteristics of structure, weight, taste, etc., 
attributed to an orange are not comprised in the 
visual impression which comes from the orange; to 
assert their existence is therefore to go beyond the 
sensation, to accomplish an act which depends upon 
indirect knowledge. Every perception resembles 
a reasoned conclusion ; it contains, like the logical 
conclusion, a decision, an affirmation, a belief, 
relating to a fact which is not directly known by 
the senses ; it is, in other words, a transition from 
a known fact to an unknown fact. 

Second. — The two acts which we are comparing 
have a common feature in implying the existence 
of certain anterior intellectual states — that is to 
say, of recollections. In formal reasoning, these 
preparatory states are called premisses. Without 
premisses, there can be no conclusion. Our mind 



84 THE PSrCHOLOGT OF REASONING. 

only accepts this proposition, "Socrates is mortal," 
because it knows the truth of a different propo- 
sition, "All men are mortal." Here there is, be- 
sides, a distinctive characteristic of all the indirect 
processes of knowledge; being indirect, they neces- 
sarily demand a proof. It matters little whether 
this proof be or be not present to the mind at the 
moment when we make use of it ; what is sufficient 
and essential is that we should have known it. 
Thus there are many simplified acts of reasoning 
whose premisses are unconscious. The majority of 
the inferences which we make daily for the practical 
needs of life are of this nature. Mr. Spencer gives 
an interesting example. 

"It is stated that Mr. So-and-so, who is ninety 
years old, is about to build a new mansion; and 
you instantly laugh at the absurdity — a man so 
near death making such preparation for life. But 
how came you to think of Mr. So-and-so as dying? 
Did you first repeat to yourself the proposition, 'AH 
men must die?' Nothing of the kind. Certain 
antecedents led you to think of death as one of his 
attributes, without previously thinking of it as an 
attribute of mankind at large. To any one who 
considered Mr. So-and-so's folly not manifest, you 
would probably say, 'He must die, and that very 
shortly,' not even then appealing to the general 
fact. Only on being asked ivliy he must die,, would 
you either in thought or word resort to the argu- 
ment, 'AH men die, therefore So-and-so must die.' 

We know, according to Mr. Spencer, that the 
syllogism represents, not the process by which the 



REASONING IN PERCEPTION. 85 

conclusion is reached, but the process by which it 
is justified; in other words, the syllogism, by con- 
veniently exhibiting the data of an act of reason- 
ing, enables us to see whether we are asserting 
more than we absolutely know, and whether the 
conclusion is really involved in the premisses, as we 
suppose it to be. The example quoted explains 
this theory. 

Returning now to the perception of an orange, 
we shall have no trouble in proving that this act 
demands, as does an act of reasoning, logical ante- 
cedents. What our eye lets us know directly is the 
impression of a yellow spot ; no one will maintain 
that we are able, apart from all experience, and by 
a kind of pre-established mechanism, to conclude 
from this sensation that there is an orange in our 
hand, a fruit which we may cut, eat, suck, and 
which quenches thirst, etc. If no experience had 
ever intervened, our intellect would see nothing 
beyond our actual sensation, and there would be 
no perception, in the proper sense of the word. If, 
on the contrary, we are able to recognize the 
orange, it is because our eye has received previous 
education ; it is because we have learned to associ- 
ate, on other occasions, a certain visual impression 
(the sight of the orange) with all the other impres- 
sions which we formerly experienced when we took 
the orange in our hands to cut and eat it. 

This is therefore the second point of contact 
between the perception of an exterior object and 
an act of reasoning. These two acts imply older 
states, recollections. These logical antecedents are 



86 THE PSrCHOLOGT OF REASONING. 

called premisses in reasoning and anterior experiences 
in perception. The premiss of the reasoning 
analyzed is, "All men are mortal." That of per- 
ception might be, strictly speaking, formulated in 
an analogous fashion: "All spherical bodies of 
yellow colour and of a certain size are fruits filled 
with a sweet juice." However that may be, we 
see that perception consists, like reasoning, in the 
application of a recollection to the knowledge of a 
new fact, and ends in the generalization of this 
recollection. 

But that is not all. 

If in the majority of reasonings the premisses 
remain unconscious, in all or almost all cases of per- 
ception, the anterior experiences which render 
them possible are recalled to the mind as little. 
Thus, when we see a certain yellow spot, we imme- 
diately affirm "this is an orange;" there is no con- 
scious return towards the past, and consequently 
no allegation of proof. It is only if we throw 
doubt upon the accuracy of our perception that we 
invoke our past experience, exactly as in our every- 
day experiences. 

Third.— We proceed with our parallel to see how 
far it is justified. We know that the foundation 
of all reasoning is the recognition of a similitude; 
reasoning may be roughly defined as the transition 
from a known fact to a second unknown fact, by 
means of a resemblance. When we mentally read 
over the following syllogism, "All men are mortal; 
Socrates is a man, therefore Socrates is mortal," 
we pass from a known fact (the mortality of men) 



REASONING IN PERCEPTION. by 

to an unknown fact (the death of Socrates), by 
virtue of the relation of resemblance which we 
discern between the two facts; this resemblance 
forms the object of a special proposition, "Socrates 
is a man. ' ' There is no act of reasoning in the world 
which does not contain, after the manner of this 
example, the afidrmation of a resemblance; but 
this affirmation takes different forms and is called 
by different names: comparison, classification, 
recognition, etc. We even know that the school 
of Aristotle compares reasoning to a classification. 
To conclude that Socrates is mortal would be to 
put Socrates in the class of men, of whom mortality 
is an attribute. 

The perception of an exterior object implies a 
similar act of identification. In order to recognize, 
with the sight alone, that we have before us an 
orange, it is not enough that past experiences should 
have formed an association between a piece of yel- 
lowish-red colour and certain characteristics of 
structure, touch, taste and weight; it is necessary, 
in addition, that a resemblance should exist between 
the two experiences, past and present ; it is neces- 
sary that the two pieces of colour should have the 
same colour, the same tint. We do not generally 
reflect in order to assure ourselves of this resem- 
blance by a voluntary act of comparison ; but it is 
none the less true that it, the resemblance, must 
exis-t. Further, we are, in the majority of cases, 
very quick to distinguish a real resemblance from a 
deceptive analogy. 

Some authors have also compared perception to 



88 THE PSrCHOLOGT OF REASONING. 

an operation of classifying, as has been done in the 
case of logical reasoning. According to them, the 
visual perception of an object would consist of 
classing the sensation which we experience in the 
group of analogous sensations which have formerly- 
been experienced. This idea has been developed 
at length by Mr. Spencer. 

In short, perception and reasoning have the 
three following characteristics in common : First, 
they belong to mediate and indirect knowledge; 
second, they require the intervention of truths for- 
merly known (recollections, facts of experience, 
premisses); third, they imply the recognition of a 
similitude between the fact affirmed and the ante- 
rior truth upon which it depends. The union of 
these characteristics shows that perception is com- 
parable to the conclusion of logical reasoning,* 

This is one of those truths which have been so 
fully demonstrated that they have found their way 
into every book. Helmholtz says in this connec- 
tion: The judgments by which we trace sensations 
back to their causes belong, by their results, to what 
are called judgments by induction ;f and in support 
of this contention, he cites the following example: 
"As in the immense majority of cases the excita- 

*We may remark that the existence of so many different definitions of 
reasoning; is due to the fact that each of them considers only one of the fore- 
mentioned characteristics. Thus, the following definition: reasoning is a 
transition frotn the knozvn to the tinknqwn, or again, reasoning is a demon- 
stration, relates to the first characteristic; the definition: reasoning is an 
extension of knoivledge already attained, relates to the second; and the 
definition: reasonijig is a classification, relates to the third. 

tinduction is inaccurate. In perception, the mind never rises so high as 
a general conclusion; it simply comes to a conclusion on the object present 
to the senses. It is an inference from particular to particular, and likewise, 
in the case where perception is aided by a considerable number of anterior 
experiences, it is a deduction. 



REASONING IN PERCEPTION. 89 

tion of the retina at the external angle of the eye 
comes from a ray of light which reaches the eye 
from the nasal side, we think it is the same in every 
new case in which the excitation affects the same 
part of the retina, just as we maintain that every 
man who is at present living must die, because 
experience has taught us that so far death is the end 
of all men." We might extract analogous quota- 
tions from the works of Mill, Spencer, Bain, etc. 

It would be easy to follow up and renew the 
comparison which we have made between perception 
and the syllogism, by remarking that if perception 
is an act of reasoning, the illusion of the senses is a 
sophism. This deduction was made long ago ; it 
has even been attempted to extract the logical rule 
which is violated by the majority of illusions. We 
may cite an example, borrowing it from the class of 
passive illusions, which have been very carefully 
studied by Mr. J. Sully.* If the finger be pressed 
upon the outside of the lowered eyelid, a kind of 
luminous ring will appear. This image, which 
represents the end of the finger, will not be local- 
ized at the point where the retina has been excited, 
but inside and above, towards the upper part of the 
nose, just at the place where the luminous source 
which affects the retina at the place touched is 
generally situated. The sophism contained in the 
unconscious reasoning consists in taking as an abso- 
lute law a rule which is only valid in certain cases. 
Errors of this kind are frequently met with in the 
physiology of the organs of the senses. 

*0p. cit., passim. 



90 THE PSTCHOLOGT OF REASONING. 

We may now consider it as sufficiently demon- 
strated that perception is an act of reasoning. We 
shall not therefore pause to discuss the opinion of 
some thinkers who insist upon drawing a line be- 
tween reasoning and inference, and wish to see no 
more than an inference in perception. According 
to these writers, inference would be the simple con- 
secution by which the mind passes from one idea to 
another, as when a Dutchman, traversing a town in 
India, expects to find a tavern in it; this operation, 
though a passage from the known to the unknown, 
would be only a pseudo-reasoning, a sketch which 
does not deserve the name of the finished work. 
But there is in reasoning, always according to the 
same writers, something more in the mind than this 
bringing together of facts. Reasoning is the reflect- 
ive act by which the mind adopts a proposition 
because it sees in it the logical consequence of 
other propositions which it holds to be true; so 
that the only rational operation is that in which all 
the premisses are present to the mind, and where 
the mind perceives the relation which binds the 
premisses to the conclusion.* 

We reject this arbitrary distinction. Inference 
or reasoning, it is always the same thing; we have 
just shown this in the case of perception, where 
analysis reveals the essential parts of a syllogism. 
How could it be maintained, after that analysis, 
that perception is a simple consecution? All that 
may be granted is that in reality certain reasonings 
are conscious and that others are automatic. Per- 

*Brochard, Logique de Stuart Mill, Revtte philos.. Vol. XII. 



REASONING IN PERCEPTION. 9I 

ception is of the second class. But great value 
should not be attached to this difference. Con- 
sciousness accompanies the physiological processes 
of reasoniiig, of sensation, of recollection, etc., it 
does not constitute them ; it is an epiphenomenon, 
and nothing more.* So far as quantitative experi- 
ments made on sensations go to prove, conscious- 
ness is subject to conditions of duration and intens- 
ity. If these conditions are realized, it exists; if 
not, it is wanting. But in every case it appears 
and disappears without disturbing the action of the 
nerve cells, which continues silently in the same 
necessary way. 

IV. 

We have just seen that the work involved in 
every perception is identical with the operation 
which consists in drawing a conclusion when the 
premisses are given. At the same time we made a 
short survey of the nature of this work. Let us go 
further, and we shall try to give an explanation of 
reasoning. 

But before approaching this great problem, to 
which this book is wholly devoted, let us pause at 
some preliminary considerations. We intend to 
give a psychological theory of reasoning. For 
this theory to be correct, for it to be even accept- 
able, it is evidently necessary that it should satisfy 
certain conditions, that it should fit certain 
psychical facts already known and considered as 
certain. Psychology is no longer in that state of 

*Ribot, Diseases of the Memory, p. "^6 (Appleton, New York), and The 
Diseases of Personality, Introduction (The Open Court Pub. Co., Chicago). 



92 THE PSrCHOLOGT OF REASONING. 

infancy which every science has known and in which 
any one may freely erect fantastic explanations 
which rest on nothing. 

In every science which has undergone organiza- 
tion, a new theory has a right to be cited only 
when it is supported by admitted facts; if, for ex- 
ample, some one pretended to have discovered per- 
petual motion, it would be right to reject his pre- 
tended discovery without examination, for it would 
be contrary to all the laws of mechanics. Psychol- 
ogy also has its questions of perpetual motion. 
Therefore, before seeking the solution of our prob- 
lem, let us put it in the form of an equation, in 
order to determine the conditions which the solu- 
tion must satisfy in order to be correct. 

First condition. — Stuart Mill remarked that all 
psychological explanations, without exception, are 
subject to a general condition ; that of being an 
application of the lazvs of association by resemblance 
and by contiguity.'^ To explain a psychological 
fact is, according to Stuart Mill, to show that it is 
a particular case of the laws of association. We do 
not intend to inform the reader what is understood 
by these laws ; the subject is well known, thanks to 
the numerous analyses of English works which we 
possess. We may merely recall the fact that asso- 
ciation by resemblance is the law by which ideas, 
images and feelings vv^hich are alike are called up in 
the mind. Thus, a portrait evokes the idea of the 
model. We may also recall the fact that associa- 
tion by contiguity is the law by which two phenom- 

*John Stuart Mill, Dissertations and Discussions, III, loS et seq. 



REASONING IN PERCEPTION. 93 

ena which have been experienced together tend to 
associate themselves in our mind, so that the image 
of the one recalls the image of the other. Such are 
the laws of association ; our cut-and-dried formulae 
can convey no idea of the immense number of phe- 
nomena which these laws explain. However, no 
one has the right to maintain that these laws are the 
only ones, and that no others exist. We cannot 
imagine that we already know all the laws of mind. 
That would be a singular presumption. So we 
believe that Stuart Mill was too exclusive in saying 
that all psychological explanations consist in reduc- 
ing the fact to be explained to the laws of associa- 
tion. What must be retained of Stuart Mill's 
opinion is that in psychology, as in all other sci- 
ences, an explanation ought to plead nothing out- 
side of truths which are at the same time known 
and established ; now, as the only psychological 
laws which we can at the present time consider as 
established are those of association, they are the 
only ones which we may provisionally introduce 
into explanations. There we have a valuable sign 
which enables us to distinguish at first sight a seri- 
ous explanation from those caricatures of explana- 
tions which are merely hypotheses built upon other 
hypotheses. 

Second condition. — For the psychologist every 
verbal proposition resolves itself into an association 
of images, and the demonstration of a proposition, 
the reasoning, is the creation of a new association. 
Reasoning has been very accurately defined by Mr. 
Spencer as "the establishment of a relation between 



94 THE PSrCHOLOGT OF REASONING. 

two things," and he has explained, with a great 
amount of detail, the meaning and the range of his 
definition. 

We have already had occasion to show that in 
every perception there is work, and that this work 
culminates in a synthesis of sensations and images.* 
The process of perceiving an object, for example an 
orange, and of recognizing the existence and nature 
of that fruit when placed before us, consists in 
associating with a visual impression a certain num- 
ber of attributes of which we do not take direct 
cognizance; but to associate two groups of quali- 
ties, is to judge; it is, as Mr. Spencer's definition 
has it, to establish a relation between two things. 

This settled, the following question arises: 
How is this synthesis formed? By what process is 
a relation established between the two things? 
How do we pass from an impression of yellowish-red 
colour received by the eye to the image of all those 
attributes which characterize an orange? Or again 
(for we are anxious to show all the aspects of the 
problem), how do tve Judge that "this is an orange?" 

Third condition. — Mr. Spencer adds a word to 
the definition of reasoning already quoted. Rea- 
soning, he says, is the indirect establishment of a 
relation between two things. This adjective will 
be fully understood by means of an example. Let 
us suppose that instead of confining ourselves to 
looking at the orange, we took hold of the fruit and 
occupied ourselves in peeling and eating it. Accord- 
ing as w^e perform these different actions, an associ- 

*See pages 70 and 81. 



liEASOAriNG IN PERCEPTION. 95 

ation becomes formed in our mind between the 
sight of the orange and innumerable sensations of 
the hand and of taste: the formation of this rela- 
tion is direct, produced by experience, it comes 
from without. On the contrary, when we perceive 
the orange at a distance, without touching it — that 
is to say, when we reason regarding our visual sen- 
sation — the relation which is established between 
this sensation and the mental image of the attri- 
butes is indirect, in the sense that it is not produced 
by actual experience, and that it is produced by the 
operation of other intellectual states — premisses. 

Let us express this fact in the precise language 
of psychology. What is a premiss? It is a judg- 
ment, an association of images. Consequently, 
what is a conclusion which follows from the prem- 
isses? It is an association of images produced by 
other associations. 

We may therefore formulate as follows the third 
question which arises: How can the two complete 
associations forming the premisses unite to form a 
third, that which constitutes the conclusion of the 
reasoning? 

We possess the touchstone with which we may 
make sure whether a psychological theory of reason- 
ing is true or false. Let us try this criterion. 

Very few of the existing theories of reasoning 
are in harmony with modern ideas and merit discus- 
sion. The spirtualistic French school, which has 
on many questions adhered to the old doctrine of 
entities, generally explains reasoning by a faculty of 
reasoning; some supporters of this school are not 



96 THE PSrCHOLOGT OF REASONING. 

content with this purely verbal explanation, but 
they confine themselves to maintaining that reason- 
ing is a simple, irreducible and consequently inex- 
plicable property. It is to be regretted that 
M. Taine, in his magnificent work On Intelligence, 
gave us a theory of knowledge instead of a psychol- 
ogy of reasoning. In Germany, Wundt places rea- 
soning at the basis of the psychical life ; he makes it 
the foundation of all our thoughts, and goes as far 
as to say that we might call the mind "a thing 
which reasons." Thus he tries to discover reason- 
ing even in the primitive and elementary fact of 
the psychical hfe, in sensation. But when it comes 
to taking the mechanism of reasoning to pieces, bit 
by bit, to explain it according to known laws, a 
gap is visible in his work. As far as we are able to 
judge, in the light of M. Ribot's analyses, which 
are always masterpieces, Wundt has not given us 
an explanation of reasoning. In England, Stuart 
Mill concerns himself almost exclusively with the 
logic of reasoning, he leaves psychology alone; and 
we know that there is as much difference between 
psychology and logic as between physiology and 
hygiene. Alexander Bain, who systematically 
reduces all mental states to a combination of the 
la\i/s of association, touches several times upon the 
question which engages us; but his thought re- 
mains vague and irresolute, and, yielding to his 
habit, he describes instead of explaining.* Only 
in Mr. Spencer's work do we find a true theory of 
reasoning. 

*See especially, in his excellent book on The Senses and the Intellect, 
pages 524 et seq. 



REASONING IN PERCEPTION. 97 

In this case the theory is as complete as could 
be wished, for it starts from the most elevated type 
of reasoning and reaches the simplest, including in 
its immense span compound quantitative reasoning, 
simple and imperfect quantitative reasoning, perfect 
qualitative reasoning, imperfect qualitative reason- 
ing, reason in general, perception, and the feeling 
of resistance. The author has tried to prove that 
the process which the philosopher follows in his 
longest and most complicated reasonings is that by 
which incipient consciousness strives to become 
thought; that, in a word, a unity of composition 
exists among all the phenomena of the intellect. 
What is this unity? The whole study of reasoning 
may be summed up by defining it as "a classifica- 
tion of relations." But what does the word classi- 
fication signify? It signifies the act of grouping 
together like relations. To deduce a relation is to 
think that it is like certain others.* 

Before this theory is discussed it must be made 
clear. We shall do this by quoting from the author 
some types of reasoning, and by showing how the 
idea of a classification of relations throws light upon 
the mechanism of these operations. 

Let us take as an example an "imperfect quali- 
tative reasoning," which treatises on logic com- 
monly give as a syllogism. When we say, "All 
horned animals are ruminants; this is a horned 
animal, therefore this animal is a ruminant," the 
mental act indicated is, according to Mr. Spencer, 
a cognition of the fact that the relation between the 

*Half of the second volume of The Principles of Psychology is devoted 
to the development of this question. 



THE PSrCIIOLOGT OF REASONING. 



particular attributes in this animal is like the rela- 
tion between the homologous attributes in certain 
other animals. It may be symbolized thus: 



(Tlic aUril)iites consti- 
tuting a horned ani- A 
mal.) 



(coexist with) 

(The attributes consti- 
tuting a ruminating 
animal.) 



B 



(The attributes consti- 
a tuting this a horned 
animal.) 



is like-| (coexist with) 



(The attriljutes consti- 
b tuting this a ruminat- 
^ ing animal.) 



"The relation between A and V> is like the rela- 
tion between a and b;" such is the formula which, 
according to the author, really represents our log- 
ical intuition. It will be noticed that reasoning 
thus understood becomes a true proportion, with 
four terms, a kind of rule of three from which the 
idea of quantity is excluded. Stuart Mill has 
reproached Mr. Spencer for making reasoning an 
operation in four terms, and he has maintained 
that in reality only three exi.st. Thus, to transfer 
the controversy to the preceding example, Stuart 
Mill has remarked that the reasoning attributes to a 
certain' animal which has horns the savic attributes 
(constituting the ruminating aniiTial) as to all the 
other animals which have horns; consequently, the 
two terms indicated by the letters W and b make 
only one, they are the same; three terms exi.st and 
not four. Mr. Spencer has replied that as these 
attributes do not belong to the .same animals, but 
to distinct though similar animals, the attributes 
also ought to be distinct. The .solution of this 
difficidty is easy to find; it seems to us that Mill is 



I^EASO.VnVG IN PERCEPTION. 99 

right. He would hav-e been able to repty to Mr. 
Spencer: Ever\' horned beast has distinct attri- 
butes which make it a ruminant, but the general 
idea which we have of these attributes is common to 
these animals; it is the same for all. And thus we 
succeed in reducing the terms of the reasoning to 
thr 



ee 



* 



That, however, is a trifling matter. Let us 
admit for a moment the existence of the four terms. 
It ma)- be granted that reasoning is a classification 
of relations; but the relations must be formed be- 
fore they can be classed, for they <^o not exist 
before being formed, and we cannot compare what 
tioes not exist. The curious thing is that this im- 
portant question is hardly touched upon by Mr. 
Spencer, anci yet he was the first to recognize that 
reasoning consists in the establishment of a relation. 
The few words which he has written on this sub- 
ject, as if by the way, relate to another example. f 
Analyzing the following syllogism, "All crystals 
have planes of cleavage; this is a crystal, therefore 
this has a plane of cleavage," he inquires how our 
mind is able to pass from the perception of an indi- 
vidual crystal to the idea of a plane of cleavage; 
and he prefers to sa)-, in order to explain the estab- 
lishment of a relation between these two things, 
which is the essential difficulty of the question: 
"Before consciously asserting that all crystals have 
planes of cleavage it has already occurred to me 
that this crystal has a plane of cleavage." But 
then, it may be objected, everything is done; the 

*Spencer, Princit'lcs of Fsycholog^y, Vol. II, p. 69. 
iOp. cii.,p.i)';, Vol. H. 



lOO THE PSrCHOLGGT OF REASONING. 

work of reasoning is accomplished, the relation is 
established, and it is precisely all this which 
required explanation. Mr. Spencer himself recog- 
nizes this, for he calls this operation, which he 
assumes to be effected without explaining its gen- 
esis, a primary or provisional inference. "This act 
is simple and spontaneous," he says, "resulting not 
from a remembrance of the before-known like rela- 
tions, but merely from the influence which as past 
experiences they exercise over the association of 
ideas."* Therefore we see that when it comes to 
the decisive moment, the theory disappears; it can- 
not be declared to be either true or false, for it does 
not really exist. 

We have still many other objections to offer. 
We might ask what, in this comparison of relations, 
the old relation, that which takes the place of 
premisses, can add to the new and inferred relation. 
When I assert that a relation exists between the 
crystal which I hold and a plane of cleavage, I find, 
it is true, a confirmation of what I assert, in repre- 
senting this old relation to myself: All crystals 
have planes of cleavage. The general rule proves 
the particular case. But it is precisely this which 
wants explanation. We have just shown this in 
stating the equation of a theory of reasoning; the 
reader will recollect that we made this point the 
third condition which a theory of reasoning must 
fulfill in order to be correct. It must be explained, 
we have said, how a conclusion follows from its 
premisses; in more accurate language, it must be 

*0p, cit.. Vol. II, p. 102. 



JRBASONIJVG IN PERCEPTION. lOl 

shown how an association between two terms can be 
formed by the medium of former associations. But 
Mr. Spencer's hypothesis is powerless to solve this 
question. What does he tell us? That the mind, 
after having formed (it is not known how) a relation 
between a and b, compares it to a before-known 
relation between A and B. But what can follow 
from this intuition of a resemblance between the 
two relations? How can the comparison of the two 
add to the bond which already unites the terms a 
and b? This is a question of mental mechanism 
which has to be solved. Mr. Spencer does not 
solve it, he does not even suspect it. It is one of 
the characteristics of the theory we are discussing 
that it does not touch this question. Mr. Spencer 
confines himself to proving that the idea that all 
crystals have planes of cleavage confirms the partic- 
ular conclusion, this crystal has a plane of cleavage ; 
but, once more, this is merely stating the question. 
It would be necessary to explain this confirmation 
of the particular relation by the general relation 
by introducing the laws of association. 

We are sorry to have to deliver such a judgment 
on a part of the work of a thinker who has done so 
much for psychology; but it is a duty to judge 
theories in themselves, without taking into account 
the fame of those whose namics are associated with 
them. 

We shall, in our turn, approach the problem of 
reasoning, putting forward some observations on a 
mental law to which we shall often appeal, the law 
of resemblance. 



CHAPTER IV. 

THE MECHANISM OF REASONING. 



The action of resemblance on the phenomena of 
the mind has been, so to speak, recognized in all 
times; it has never been very difficult to discover 
that one idea suggests a like one. Mr. Bain, who 
has devoted a long chapter, full of facts, to 
association by resemblance, enunciates in the fol- 
lowing terms the law which governs this association : 
"Present actions, sensations, thoughts or emotions 
tend to revive their like ■bsc^.ow^ previous impressions 
or states."* This is a very wide formula, for it 
includes not only ideas, but emotions and actions; 
nevertheless, it seems to us to be incomplete upon 
a most important point. 

The reproductory action of resemblance — the 
attraction of sameness — is a common and superficial 
effect, known to us since the days of Aristotle ;f 
resemblance has in reality a second effect, quite as 
important as the first — that of fusion. Alongside 
the law of suggestion and of recollection by resem- 
blance, we may place the Law of Fusion. 

It may be enunciated as follows, the demonstra- 

*Bain, The Senses and The Intellect, p. 463 ; J. Stuart Mil', Examina- 
tion of Sir William Hamilton's Philosophy, p. 225; Cf. Ribot, La psycho- 
logie anglaise contemporaine . 

fOn this subject Hamilton's Dissertation at the end of his edition of 
Reid, may be consulted. 

102 



THE MECHANISM OF REASONING. 1 03 

tion being left for later consideration : "When two 
like states of consciousness are present to our. mind 
simultaneously or in immediate succession, they 
become fused together so as to form a single state." 
Thus, when two sounds of the same pitch and the 
same timbre vibrate at the same time, the most 
practiced ear does not dissociate them ; only a 
single reinforced sound is heard ; each sound loses its 
individuality in a single resultant. If the two states 
of consciousness are exactly alike, the fusion is com- 
plete ; if they present only an imperfect resemblance, 
implying a partial sameness, the fusion is partial. 

The fiision of like sensations. — The best illustra- 
tion of our law as regards sensations is furnished by 
the sensations of touch, in Weber's experiment. 
This experiment shows us the fusion of like sensa- 
tions ; they fuse so thoroughly that a person who 
has not been told beforehand that he is receiving 
two sensations produced by two distinct excitations 
believes, while he experiences only a single sensation, 
that his skin is bearing only a single pressure. 
But this phenomenon touches upon a much dis- 
cussed problem in physiology, upon which we must 
first of all say some words of explanation. 

Among all the senses, touch is the one which 
occupies the largest surface ; while the special senses, 
sight, hearing, smell and taste, are confined to ex- 
tremely small parts of the organism, that of touch 
is found over the whole extent of the skin and 
even on some mucous membranes; the nasal fossae, 
the conjunctiva, the buccal cavity, the two extrem- 
ities of the digestive tube, and the urethral canal 



I04 THE PSrCHOLOGT OF REASONING. 

give us sensations of contact. This wide diffusion 
of the sense of touch over the surface of the body 
is explained by the fact that touch is the funda- 
mental and primitive sense from which the special 
senses have been derived by a progressive differenti- 
ation, and which perhaps will, in the course of 
time, give rise to the formation of new special 
senses. The sense of touch is not equal all over; 
certain divisions of the general epidermis display a 
delicacy superior to that of the others. For ex- 
ample, we know that the tactile sensibility is dull 
on the middle of the back; it is keener on the 
hand, keener still on the tips of the fingers; the 
highest degree of sensibility is reached at the end of 
the tongue. Weber succeeded in measuring these 
differences in sensibility by employing a pair of 
blunt compasses, the two points of which he shifted 
over the surface of the body. He found that on 
the middle of the back the two points are not felt 
double until they are thirty-nine lines apart (a line 
=0.88 inch); when closer, the two points produce 
only a single sensation. On the chest the necessary 
distance is twenty lines ; on the thigh, sixteen ; on the 
lower part of the forehead, ten; on the palm of the 
hand or the end of the nose, three ; on the edge of 
the lower lip, two ; on the tip of the index finger, 
one; on the point of the tongue, one-half. 

These experiments in measurements have given 
rise to a new problem. It has been asked why two 
compass points produce, according to their distance 
apart and the region of the body on which they are 
placed, sometimes two sensations, sometimes one. 



THE MECHANISM OF REASONING. 105 

Two explanations have been proposed. The 
first, simple after the manner of all a priori views, 
consists in saying that where two points are felt, 
each of them has separately excited a nerve fibre, 
and that, on the other hand, when we feel only a 
single point, the points of the compass have excited 
only a single fibre. In every case we experience as 
many sensations as there have been nerves excited. 
A trace of this explanation remains in the language, 
in the term ccrcle dc sensation. If one of the two 
points of the compasses be pressed on the skin, 
and if it be tried up to what distance from the first 
point the second fails to produce a new sensation, 
an area is thus circumscribed which has the form of 
a circle or of an ellipse. This area, being capable 
of receiving only a single sensation, corresponds, 
according to the theory, to the territoiy of one 
nerve fibre ; it is called the circle of sensation. 

This explanation contains a part of the truth. 
There is no doubt that the portions of the integu- 
ment whose sensibility is very delicate are richer in 
corpuscles of touch than the portions whose sensi- 
bility is dull. But this is a very different thing 
from admitting that every circle of sensation is, as 
has been said, an anatomical unit, the territory of a 
single fibre. There are places where the points of 
the compass may be separated by more than a 
dozen nerve papillae without producing any more 
than a single impression. We may add that the 
limits of a circle of sensation vary strikingly under 
the influence of attention and of practice ; if a circle 
really corresponded to the province of a single fibre, 



Io6 THE PSJ'CHOLOGT OF REASONING. 

this would be an invariable unit. Finally, there is 
a more conclusive fact than all the others. If two 
circles of sensation, whose circumferences are 
tangential, are drawn upon a person's forearm, and 
if one of the points of the compasses be placed in 
one circle and the other in the other, the two being 
brought as near together as possible, the person 
undergoing the experiment will experience only 
one sensation; in order to produce two, the points 
must be separated by the whole diameter of a 
circle. If it were true that each circle was supplied 
by a special fibre, it would be sufificient for the two 
points to be placed upon any points whatever in 
the two circles for the person to feel both of them. 

The second explanation is known under the 
name of the tJieory of nerve fields. It is observed 
that for two sensations of touch to be distinguished 
there must be between the excited points on the 
skin a certain space, a certain number of nerve 
ramifications, a nerve field. Only this distance is 
necessary, and it is suf^cient. Why is it so? Be- 
cause, it is said, two things can only be distin- 
guished if something separates them. The excita- 
tion of the two nerve fibres can only produce two 
distinct impressions if these two fibres are separated 
by unimpressed nerve elements. These elements, 
whose role is to divide the two sensations, are 
represented by the distance apart of the two points 
of the compass. 

This pretended explanation seems to us to be 
simply a tautology ; it af^rms the necessity for the 
separation of the points, which is a fact of observa- 



THE MECHANISM OF REASONING. lOj 

tion ; but it is not apparent what can be the role of 
the intervening nerve fibres, since nothing produces 
an impression upon them. The theory of nerve 
fields is powerless to explain this. 

The explanation which I propose to substitute 
for the preceding ones may be summed up in a few 
words. I assume that every point on our epidermis 
has a special way of feeling; the quality of the sen- 
sation varies with the region of the skin ; for ex- 
ample, when the forehead, then the cheek, chin, 
neck and the nape of the neck are pressed by the 
finger, a different tactile sensation is produced every 
time. This variation always takes place in a con- 
tinuous manner from one point to another; if we 
chose two points close together it might happen 
that the difference between the two sensations 
would be too slight to be perceived, and that the 
two sensations would behave practically as if they 
were identical. The distance at which the two sen- 
sations may be distinguished in consciousness is not 
uniform over the whole body, for the local quality 
of each sensation does not vary equally all over. 
This being admitted — and we shall shortly enumer- 
ate the arguments which prove our hypothesis — 
what will happen? By exciting two points on the 
skin with the compasses, we may produce at pleas- 
ure, according to the distance apart of the points 
and the region of the skin, two different sensations 
or two similar sensations; they will be different 
when the points on the skin are far enough apart 
for their difference of sensibility to be appreciable; 
they will be ahke when the points selected are suf- 



Io8 THE PSrCHOLOGT OF REASONING. 

ficiently near to each other for their sensibihties to 
appear the same in kind. 

Now, in the case of two different sensations, the 
subject will feel the two points distinctly; in the 
case of two similar sensations, these sensations will 
become fused into one, and the subject will feel 
only one point. 

Weber's experiment would be explained, accord- 
ing to this hypothesis, by the fusion of similar sen- 
sations; it would be an illustration of the law of 
fusion. But what must be added to demonstrate 
the truth of this hypothesis? Two things must be 
proved : 

First. — That the sensations produced by the two 
points of a pair of compasses are of different quality 
when the subject perceives the two points. 

Second. — That the sensations produced by the 
two points of a pair of compasses are of the same 
quality when the subject perceives a single point. 

Lotze, Wundt, Helmholtz and others in Germany 
have attributed a difference of sensibility to the 
different regions of the body. This is what is called 
the tJieory of local signs. We shall choose one, the 
most striking, from among the proofs of this theory : 
it is derived from the phenomenon of localization. 
When we touch a person on any part whatever of 
his body, he feels and at the same time he localizes 
the excitation. This knowledge of place is not 
innate; it is acquired. It is formed, in all prob- 
ability, in the following manner: We have learned 
by experience that when we feel a certain tactile 
sensation, a pressure is produced on the arm ; a 



THE MECHAiVISM OF REASONING. 1 09 

certain other sensation corresponds with an action 
on the toe, and so on. In the course of time we 
have connected a definite sensation with the sight 
of our arm, another with the sight of our toe, and 
finally each different sensation with the sight of a 
different point on our skin. When we come to 
press, prick or pinch our body, the sensation proper 
to the part affected awakens the ocular image of 
that part by the mere power of association. It is 
a mental law that when two sensations have been 
experienced in contiguity they adhere in such a way 
that the one presented suggests the other. In the 
present case the suggestion is effected so rapidly 
that the visual image of the part touched follows 
the tactile sensation immediately. Localization is 
nothing else. As regards the position of the point 
touched, it is given us by our muscular activity. 
This explanation of the genesis of the sense of place 
always assumes one thing: that two sensations of 
contact which are referred to two different parts of 
the body both possess a local sign which distin- 
guishes them and prevents them from being con- 
founded with each other. Suppose all our sensa- 
tions of contact were absolutely uniform. A per- 
son pricked on the finger will not-know whether it 
was on his finger or his toe, for if his toe had been 
pricked he would have experienced the same sen- 
sation. For one sensation of contact to become 
associated with the sight of the finger, and another 
with the sight of the toe, it is absolutely necessary 
that the two sensations be different ; otherwise they 
will be confounded with each other, and the sensa- 



no THE PSrCHOLOGT OF REASONING. 

tion whose seat is at the finger will be able to sug- 
gest indifferently the ocular image of quite another 
part of the body. 

In short, localization implies distinct sensations. 
This fact puts us in a position to know when the 
two sensations produced by the compasses are sim- 
ilar or different. Are they susceptible to being 
localized in a distinct manner? Then they are 
different. Are they not susceptible of distinct 
localization? Then they are similar. 

By making use of this criterion, we find that in 
every case in which the two sensations are felt 
double the subject can localize them, which proves 
that they are of different natures. For example, I 
press the two points of my compasses transversely 
on a person's forearm, the points being thirty-nine 
lines apart, the distance necessary for the subject 
to feel each point separately. Then I lift the two 
points up alternately, asking the person, whose 
eyes are shut, to inform me if it is the right or the 
left one he continues to feel. He replies correctly 
every time; he localizes exactly. This is plain 
proof that each of these sensations differs a little 
from the other. Thus in the case where the sub- 
ject perceives two points, there are two different 
sensations, as is proved by the possibility of distinct 
localization. 

Conversely, we have to investigate if it is pos- 
sible for the subject to give a different localization 
to two sensations which, simultaneously produced, 
have the effect of a single sensation. We try 
experimentally how far apart we may put the two 



THE MECHANISM OF REASONING. m 

points without their ceasing to be confounded with 
each other, and we mark with ink the points on 
the epidermis at which they are placed. It is 
always well not to go as far as the maximum dis- 
tance, for it varies a little during the course of the 
investigation, merely by attention and exercise; it 
might therefore happen with the maximum dis- 
tance that the two sensations, which were at first 
similar, became in a moment different, a condition 
of things which would disturb the experiment. 
After these preparations, we excite alternately the 
two points marked with ink, asking the subject to 
state, with his eyes shut, upon which one the 
instrument is placed. The subject does not succeed 
in this, or, if he tries to localize, he does so with 
alternate success and failure, which proves that he 
is guessing. This inability to localize the two sen- 
sations can depend upon only one cause, the sim- 
ilarity of the two sensations. 

It is therefore true that the experiment with the 
compasses gives us an example of the fusion of two 
similar sensations. This is all that we wished to 
show.* 

In the preceding experiment the sensations 
which are fused together are exactly, or almost 
exactly, alike, and the fusion resulting from their 
being brought together is total. Let us give an 
example of partial fusion. A partial fusion often 
exists in a series of sensations which succeed one 
another, and each of which resembles, in part only, 



*For further details I may refer to my article on the Fusion des sensa- 
tions semblables {Revue j>hilosophiqMe, September, 1880). 



112 THE PSrCHOLOGT OF REASONING. 

that which precedes and that which follows it. 
This is what occurs in the zootrope, thaumatrope, 
phenakistoscope, dedaleum, cinematograph, etc. 
These scientific toys are designed to produce a 
series of impressions on the retina of the observer, 
representing the successive phases of any periodic 
movement, for example, a man who juggles with 
his head. 

Each figure in the zootrope, taken separately, 
differs very little from its neighbour on the right 
and on the left; their resemblance may be ex- 
pressed by the following letters abc, bed, cde, def, 
efg, fgh, etc., which indicate the portion common 
to two successive impressions. When the toy is 
put in motion and its rotation is sufficiently rapid, 
the impressions become fused together by their 
common points and give us the illusion of a single 
person, always the same, who makes the move- 
ments. 

The study of the mechanism of this illusion is 
the more interesting because it artificially repro- 
duces what occurs every time that we perceive a 
body undergoing changes of form or position, for 
example, a trotting horse.* 

We prefer to collect facts rather than linger 
over explanations which will come of their own 
accord. Let us confine ourselves to anticipating 
a possible objection by showing that the fusion of 
zootropic images is effected in the brain and not, as 
one might believe, in the retina. This is proved, 
first of all, by the fact that the consecutive visual 

*CliHoid has, by extending the idea of the zootrope, denied that the 
world can be continuous. 



THE MECHANISM OF REASONING. 113 

images which are produced in this fusion have a 
cerebral seat (see above, page 44). In the second 
place, there is the more direct proof that the fusion 
is not produced en bloc, but only between the sim- 
ilar portions of the images, which implies a power 
of analysis which is certainly wanting in the retina. 
TJie fusion of similar images. — Images fuse 
together like sensations, a fact which is understood 
once their nature is known, for they are revived 
sensations. It often happens that a succession of 
images, partially similar, passes across the field of 
the mind, producing appearances of transformation 
comparable to those of the zootrope. One of Mr. 
Galton's correspondents, the Rev. George Hensiow, 
sees, every time he shuts his eyes and waits a short 
time, the clear image of some object. This object 
changes its form for as long as Mr. Hensiow 
watches it. It is noticed, in studying the series of 
successive forms, that the passage from one to the 
other is supplied sometimes by relations of con- 
tiguity and sometimes by relations of resemblance. 
In one of these experiments the following images 
were seen: A cross-bow, an arrow, a person 
shooting the arrow, his hands alone being visible ; a 
flight of arrows completely occupying the field of 
vision ; falling stars ; large flakes of snow ; a land- 
scape covered with a sheet of snow ; a rectory 
with its walls and roof covered with snow ; a spring 
morning, with a brilliant sun, and a bed of tulips; 
the disappearance of all the tulips with the excep- 
tion of one; the single tulip becomes double; its 
petals fall off rapidly, there is nothing left but the 



114 THE PSrCHOLOGT OF REASONING. 

pistil; the pistil enlarges, and the stigmata change 
into three branching brown horns; a knob; the 
knob bends and becomes a stick; then a sort of 
pin passing through a metal plate, and so on. 
The experimenter has sometimes succeeded in com- 
pleting what he calls a "visual cycle" — that is to 
say, returning to the original image and going 
through the same series of forms anew. These 
visions recall that of Goethe, in whose case the 
cycle was shorter. "When I closed my eyes and 
depressed my head," relates the German poet, "I 
could cause the image of a flower to appear in the 
middle of the field of vision ; this flower did not 
for a moment retain its first form, but unfolded 
itself and developed from its interior new flowers, 
formed of coloured or sometimes green leaves. 
These flowers were not natural flowers, but of fan- 
tastic forms, although symmetrical as the rosettes 
of sculptors. I was unable to fix any one form, 
but the development of new flowers continued as 
long as I desired it, without any variation in the 
rapidity of the changes." 

It is plain that the transformation of the imag- 
inary object is produced by a succession of images. 
But it is important that the nature of this succession 
should be clearly understood. The images are not 
simply substituted one for another, the last to 
arrive expelling the preceding one ; if things occurred 
thus, we would have distinct images replacing each 
other, and not a single image which is metamor- 
phosed. It must be understood that each of the 
images is fused with the preceding one by virtue of 



THE MECHANISM OF REASONING. 1 15 

the common points which they offer, and that, 
besides, the two successive images co-exist during a 
very short instant. Thanks to these two condi- 
tions, the two images form a whole and give the 
appearance of a single image undergoing modifica- 
tion. 

The hallucinations of the insane often present 
the same evolution of forms. Magnan relates that 
an alcoholic inebriate saw upon the wall cobwebs, 
ropes, nets with contracting meshes; in the middle 
of these meshes and strands, black balls appeared, 
which enlarged, became smaller, took the form of 
rats, cats, passed across the strands, leaped upon 
the bed and disappeared.* In rarer cases the 
metamorphosis requires years. A young girl who 
had become insane in consequence of an attempt to 
assassinate her, continually saw the fist and the arm 
of the individual who had attempted to kill her. 
Now, the disease following its course, the hallu- 
cination underwent a curious transformation. The 
image which was seen by the young girl became 
modified thus: Two eyes appeared on the fist of 
the assassin, his arm became excessively long, and 
finally the hallucinatory image changed into a 
serpent. f In other cases the outline of the hallu- 
cination remains constant, but the dimensions 
change. In an old observation by Beyle, a patient 
saw an ordinary cobweb, which grew to the point 
of filling the whole of his room and suffocating 
him. Dreams supply innumerable examples of 

*Magnan, De Palcoolisme, p. 56. 

tMax Simon, Le monde des reves, p. 118. 



Il6 THE PSrCHOLOGT OF REASONING. 

these kinds of transformation ; sometimes two dis- 
tinct persons are seen blending into one; or the 
same person changes his physical personality, etc. 
The dream is the true type of metamorphic hallu- 
cinations.* 

We mention these morbid cases because the 
phenomenon which we are studying is therein 
magnified and more easily examined. But we also 
meet excellent examples of the fusion of images in 
the normal operations of life. According to Hux- 
ley, the formation of general ideas would be 
effected by the union, the fusion, the coalescence 
of several images of individual objects; and in order 
to express his thought better, the naturalist-philos- 
opher makes use of an ingenious comparison, drawn 
from the Composite Portraits which we owe to Mr. 
Francis Galton's invention.f "This mental opera- 
tion may be rendered comprehensible, ' ' says Huxley, 
speaking of the generalization of an image, "by con- 
sidering what takes place in the formation of com- 
pound photographs — when the images of the faces of 
six sitters, for example, are each received on the same 
photographic plate, for a sixth of the time requisite 
to take one portrait. The final result is that all 
those points in which the six faces agree are brought 
out strongly, while all those in which they differ 
are left vague; and thus Avhat may be termed a 
generic portrait of the six, in contradistinction to a 

*J. Sully, op. cit., p. 163; and Maury, Sommeil et reves, p. 146. M. 
Delboeuf has compared the metamorphoses in dreams to dissolving views: 
" It is," he says. " as if we projected two pictures on the same screen, and at 
the same place, by means of two magic lanterns, and illuminated one while 
the other was being extinguished." i^Revue philos., June, 1880). This ex- 
planation confirms ours, it does not destroy it. 

tGalton, Inquiries into Human Faculty and its Development (Ap- 
pendix: Generic images') . 



THE MECHANISM OF REASONING. 117 

Specific portrait of any one, is produced.* This 
beautiful invention has, it appears, already pro- 
duced brilliant results. By combining in a single 
photograph five medals representing Cleopatra, 
which, far from giving an idea of the beauty of that 
celebrated queen, had a hideous appearance, a 
much more pleasant composite portrait was obtained. 
It is probable that the points of resemblance be- 
tween the different likenesses were reinforced in 
this resultant, and that the points of difference 
remained unaccentuated {fious)\ so that we may 
reasonably maintain that the composite portrait has 
a better chance of being like the model than its 
components. Photographs of individuals belonging 
to the same classes have also been combined by this 
method, and thus certain types, as for example, 
the swindler type, have been obtained. This 
method will perhaps become useful to criminal 
anthropology in the future. 

Huxley's comparison between these composite 
photographs and concepts has been accepted by 
many psychologists; it has been regarded as very 
probable that the generalization of an image is 
formed in the mind like the generic photograph on 
the sensitive plate, by the superposition of particu- 
lar impressions. We may add a corroborative 
argument. M. Pouchet has remarked that the con- 
secutive images of his microscopic preparations 
which, as we have already seen, sometimes ap- 
peared to him after a long interval, do not represent 
any preparation in particular, but are like the vicait 

*Huxley, Hume {English Men of Letters Series), p. gj. 



Il8 THE PSrCHOLOGT OF REASONING. 

of a series of preparations of the same kind. This 
fact tends to show that the generic image is the 
result of the coalescence of several particular im- 
pressions united into a single one. 

However, it would be very unscientific to 
explain a mental operation by a comparison with a 
purely mechanical phenomenon, unless that com- 
parison implicitly assumed the existence of a prin- 
ciple of fusion. The formation of generic images is 
explained by the principle of fusion; particular 
impressions, becoming fused together, form a 
generic image because their common parts are fused 
together and are brought out strongly, while the 
parts which differ remain separate and become 
vague. 

The comparison between the generic image and 
the composite photograph is only accurate in so far 
as it illustrates this mental law ; taken literally, it 
is not rigorously exact. If the eye of a man, says 
Galton, be put in the place of the object glass of 
the apparatus used in obtaining composite portraits, 
the image which would be formed in his brain would 
not be identical with the composite portrait. For, 
contrarily to the photographic effect, the physiolo- 
gical effect of an impression is not proportional to 
its duration or its frequency; we know that, accord- 
ing to Weber's law (a disputable law, whose fault is 
that it is too precise), the sensation varies as the 
logarithm of the stimulus; in order that the sensa- 
tion may follow an arithmetical progression, the 
stimulus must follow a geometrical progression. 
We may also add the disturbing effect of attention, 



THE MECHANISM OF REASONING. I19 

of emotion, of preconceived ideas, and of a great 
number of other factors, which prevent the mind 
from fusing several images together with the exact- 
ness of a photographic plate. 

We have given a sufficient number of examples 
to make it clearly understood in what the fusion 
of sensations and of images consists. It seems 
impossible that a phenomenon so easy of observation 
should have passed unnoticed. Among the authors 
who have alluded to it we may first of all mention 
Herbert Spencer. Defining a state of conscious- 
ness, this author says that it is "any portion of 
consciousness which occupies a place sufficiently 
large to give it a perceivable idividuality ; which has 
its individuality marked off from adjacent portions 
of consciousness by qualitative contrasts, and which, 
when introspectively contemplated, appears to be 
Jiomogencous.'''^ It follows from this definition that 
if the portions adjacent to the state considered are 
not different, they form part of the same state; 
but to say that is to implicitly recognize the prin- 
ciple of fusion. Later on Mr. Spencer adds: 
"The requisite to the existence of two feelings is 
some difference.' '\ Therefore, if there is no differ- 
ence, there is a single state, that is to say a fusion 
of the two states into one. These few quotations 
show us that Mr. Spencer has observed, at least in 
passing, the phenomenon of fusion, but without 
comprehending its importance. 

Mr. Bain has made a few remarks on the same 
phenomenon. "In the case of perfect identity 

*Spencer, Principles of Psychology, Vol. I, p. 164. 
to/, cit.. Vol. I, p. 167. 



I20 THE PSrCHOLOGT OF REASONING. 

between a present and a past impression, the past 
is recovered and fused with the present, instantane- 
ously and surely. So quick and unfaltering is the 
process that we lose sight of it altogether; we are 
scarcely made aware of the existence of an associat- 
ing link of similarity in the chain of sequence. 
When I look at the full moon, I am instantly im- 
pressed with the state arising from all my former 
impressions of her disc added together."* The 
description refers to a case which we shall consider 
presently : the fusion of a sensation with an image. 
Elsewhere the same author speaks of cases in which 
we are cognizant of an identity without being 
able to say what the identical thing is, as for 
example when a portrait gives us the impression 
that we have seen the original, without our being 
capable of saying what the original is. The iden- 
tity has struck our mind, but the restoration is not 
made. Everybody knows that very singular feel- 
ing of "already seen." Mr. Bain explains it by 
the absence of recollection of the different parts of 
the object identified. In fact, in order that the 
mind may perceive the resemblance between two 
images, they must differ a little; if they do not, 
they become added together and form a single 
image, Lotze expresses the same idea with a 
lourdeur which is quite German: ''We should 
know nothing whatever of this fact, the reproduc- 
tion of a former a by the present A, if the two 
were simply present, with no distinction between 
them, at the same time. To know the present A 

*B<lin, The Senses and the Intellect, p. 466, 



THE MECHANISM OF REASONING. 1 21 

as repetition of the former a, we must be able to 
distinguish the two ; and we do this because not 
only does the repeated A bring with it the former 
one which is its precise counterpart, but this former 
one also brings with it the ideas c d, which are 
associated with it but not with the present A, and 
thereby testifies that it has been an object of our 
perception on some former occasion, but under 
different circumstances."* 

This fusion has also been described by Wundt 
under the names of assimilation and sinniltancoiis 
association. "The perception which results from 
the actual excitation of any one of the senses com- 
bines with a representation reproduced by mem- 
ory. ' * Finally, it is only right to recall that 
Ampere had, long before Wundt, described and 
analyzed the phenomenon, which he called concre- 
tion. It was Ampere, M. Pilon tells us in a lumin- 
ous article on the Formation des id^es abstraites et 
ginirales,\ it was Ampere who first showed that the 
images of former sensations modify our actual sen- 
sations to the point of making us see more than we 
see, and hear more than we hear. A man speaks 
to us in a language which is quite unknown to us; 
why do we not distinguish what he utters, while if 
he speaks in a familiar language, we clearly per- 
ceive every word he pronounces? It is, replied 
Ampere, by reason of the concretion which takes 
place between the present sensations of sounds and 
the images of those same sounds which we have 

*Meiafhysik, Book III, Ch. II. 

\Critique i>hilosophique. Vol. I, No. 3. (New series.) 



123 THE PSrCHOLOGT OF REASONING. 

often heard. "If the words which are sung in the 
Italian opera," he said again, "are not pronounced 
strongly, the listener seated at the back of the the- 
atre receives the impression of vowels and musical 
modulations only; but he does not hear, and there- 
fore does not recognize, the words pronounced. If 
he then opens the book of words of the opera, he 
will, by following them with his eyes, hear quite 
distinctly these same utterances which he was 
unable to catch a moment before. What has hap- 
pened to him is this. The sight of the characters 
before his eyes, forming not only the visual sensa- 
tion of the moment, but images of sensations of the 
same kind which he has experienced in learning to 
read Italian, the sight of the written words awakens 
in him the sonorous and acoustic images of the 
words pronounced, and the images of the sounds 
reinforcing in his mind the too feeble impressions 
received from the stage, the result is that he hears 
distinctly."* 

Here our quotations cease. They suflfice to 
show that our study of the fusion of similar states 
of consciousness is altogether without originality, 
for this phenomenon has been perceived by a num- 
ber of authors. 

While not wishing to exhaust this subject, we 
desire to say a few words on its physiological 
aspect. We have this moment seen the role re- 
semblance plays in the sphere of sensations and 
images: it suggests and fuses. The first effect is 
better known than the second. However, we 

*Fhilosophie des detcx Ampere, p. 37. 



THE MECHANISM OF REASONING. 123 

believe that we have placed the fusion of similar 
sensations and also of similar images beyond doubt. 
We even infer, by means of induction, that this 
phenomenon occurs every time that we perceive a 
resemblance, from the insignificant act which makes 
us recognize a friend, to the flash of genius which 
discerns an identity between the most remote phe- 
nomena, such as the fall of a stone and the force 
which urges the moon towards our globe. 

It remains to discover whether there exists a 
physiological phenomenon which might be consid- 
ered as the basis of this double property of resem- 
blance. 

We may assume as exceedingly probable that 
two states of consciousness which resemble each 
other totally or in part, must in general involve the 
entering into activity of the same fterve elements, 
cells and fibres, totally or in part — that is to say, to 
the same degree. This hypothesis appears to us 
to be a necessary consequence of the principle of 
cerebral localizations, according to which all im- 
pressions of the same kind affect the same part of 
the brain. But it is by no means necessary that 
the rule should be made absolute ; we are inclined 
to admit that there exist in the brain non-differen- 
tiated territories, where even similar impressions 
may affect distinct points. After having made this 
restriction in our hypothesis, we may mention some 
of the numerous facts which militate in its favour. 

We all know the involuntary mistakes which 
make us pronounce one word instead of another. 
Lewes records that he was one day relating a visit 



124 THE PSrCHOLOGT OF REASONING. 

to the epileptic hospital, and, intending to name 
the friend, Dr. Bastian, who accompanied him, he 
said, "Dr. Brinton," then immediately corrected 
this with "Dr. Bridges;" this also was rejected, 
and Dr. Bastian was pronounced. "I was," he 
says, "under no confusion whatever as to the per- 
sons, but, having imperfectly adjusted the group 
of muscles necessary for the articulation of the one 
name, the one element which was common to that 
group and to the others, namely B, served to recall 
all three." M. Ribot, from whom we borrow the 
preceding quotation,* has made an analogous obser- 
vation on mistakes in writing. Wishing to write 
''doit de bonnes,'' he wrote ''donne;'" wishing to 
write ' ' ne pas /aire une pai't, ' ' he wrote ' ' ne part 
faireJ" We may again remark that in patholog- 
ical paraphrasiSs and paragraphias the confusion is 
often produced also by an identity of letters or by 
consonance. 

All this is explained, as the authors just quoted 
observe, by supposing that the same nerve elements 
enter into different combinations, and that for 
example the names of Bastian, Bridges and Brinton 
correspond to complexus of cells which have a com- 
mon element, the element which corresponds to B. 
Thus the psychical quality of the resemblance would 
find its anatomical counterpart in an identity of seat. 

A phenomenon analogous to paraphrasia may 
be produced in oneself at will by setting one- 
self the problem of finding a proper name which 
one knows but which is not before the mind at the 

Diseases of Memory, p. 29. (Appleton, N. Y.) 



THE MECHANISM OF REASONING. 1 25 

time. Experimental psychology may thus be studied 
without a laboratory. One day I tried to recall 
to mind the name of one of my friends to whom I 
wished to write a letter; this friend is called 
M. Truchy. I did not succeed in finding his name 
again immediately. I passed through the follow- 
ing intermediate steps, which I noted down accord- 
ingly, for they afford a beautiful example of para- 
phrasia: 

Morny 

M.ouchy 

Suchy 

Qruchy 

T7-uchy 

At each efifort of memory I gained one or two 
correct letters. The course of the experiment 
seems to show clearly that the letters common to 
the series of names involve the excitation of the 
same nerve elements.* 

We may therefore accept as a very likely hypothe- 
sis that the resemblance between two states of con- 
sciousness generally has its physiological counter- 
part in an identity of seat of the nerve process. 
This hypothesis has moreover been already pointed 
out by Mr. Spencer. Every image, he says, tends 
to aggregate with like images by virtue of the iden- 
tity of their cerebral seat. 

We may now make our deductions. First of 
all, it becomes possible to explain the suggestive 
action of resemblance physiologically. That every 

*Many other proofs might be mentioned. For example, repetition 
strengthens the association of two images, or of two movements; how could 
that Be explained without admitting that the same nerve elements receive 
impressions at every repetition? etc. 



126 THE PSrCHOLOGT OF REASONING. 

state of consciousness has the property of reviving 
those similar to it, is due to the complexus of cells 
which correspond to the excitative state and to the 
state excited having common points, by which the 
nerve wave flows away from the first group of cells 
into the second. It is equally easy to understand 
the fusion of two similar states into one, since 
they have a numerically single nerve element as 
their basis. 

This hypothesis has a second advantage ; it 
explains how a resemblance between ideas is effect- 
ual even when it is not recognized by the mind. 

Psychologists are asked what may be properly 
understood by a resemblance which would not be 
perceived. Resemblance, it has been said, implies 
a mental comparison, and when this comparison is 
absent, when there is no consciousness, the resem- 
blance can no longer exist (Penjon). The true 
solution of the difficulty seems to us to be as follows : 
It is true that there is no resemblance without the 
consciousness of the resemblance, for the two things 
are in reality only one. But consciousness is only 
an epiphenomenon, superadded to cerebral activity, 
and capable of disappearing without the corre- 
sponding nerve process being altered. Two similar 
images succeed each other in our mind. It matters 
little whether we did or did not notice their resem- 
blance, for, being similar, they will put a common 
cell element in vibration. This identity of seat will 
be sufficient to produce all the results which are 
produced by a resemblance which is recognized and 
judged by a conscious comparison. 



THE MECHANISM OF REASONING. 127 

Thus it happens that an image suggests one sim- 
ilar to it, without consciousness participating in the 
act. Is it not, moreover, in this way that sugges- 
tion by resemblance operates? Like automatically 
evokes like ; when the act is accomplished, reflexion 
intervenes to give an account of what has happened, 
and it is only then that we discover the existence of 
a resemblance in the chain of ideas. M. Pilon has 
developed the same idea with his usual lucidity. 
"We must distinguish," he says, "between associa- 
tion by resemblance and the perception of the 
resemblance. It is not by means of the relation of 
resemblance perceived between two ideas that one of 
these ideas may suggest the other; for this percep- 
tion of resemblance implies that the two ideas are 
present to the mind, and consequently that the 
association is already formed. To say that resem- 
blance is an element in association is simply to say 
that one idea has the property of suggesting another 
idea which the mind then recognizes, by means of 
the faculty of perceiving relations, as similar to the 
first." {Op. cit., p, 194.) 

Another deduction of the same kind as the pre- 
ceding one is that the formation of general ideas 
must take place without the intervention of the 
self, in the same manner as suggestion by similar- 
ity and for the same reasons, by the sole virtue of 
the images raised ; or, in more accurate terms, by 
the effect of the identity of seat of the particular 
impressions. Images have the property of organ- 
izing themselves into general images, as they have 
the property of suggesting similar images. Thus 



1 38 THE PSrCHOLOGT OF REASONING. 

we possess general ideas which are produced in us 
entirely by themselves, such as the general idea of 
a chair, a knife, etc. 

It will perhaps be thought that these views of 
cerebral physiology, although they may be hypo- 
thetical, have the advantage of according with the 
prepossession of many psychologists who seek the 
explanation of mental operations in the properties 
of the nervous system. Here we have the oppor- 
tunity of showing what this prevalent opinion is 
worth, it being more correct in appearance than in 
reality. Let us admit, for an instant, that it is not 
merely probable, but absolutely demonstrated 
that two similar states of consciousness have a 
single nerve element in the brain as their basis, and 
that this unity of seat explains the two effects of 
resemblance: suggestion and fusion. Does any one 
by chance believe that we have here, in the proper- 
ties of the nervous system, a true explanation of the 
properties of resemblance? That would be a singu- 
lar illusion. For this is no explanation whatever, 
but simply a transposition into physiological terms 
of the phenomenon which is claimed as explained. 
What is this single element which we state to be the 
basis of resemblance? How can we understand its 
unity if we have not the idea of number, of plurality, 
and is this idea not at least more complex than 
that of resemblance? ""Nous voila mi rouet,'' as 
Montaigne said. 

The truth is that we can only know exterior 
things by referring them to the laws of our mind, 
and that consequently the study of one of these 



THE MECHANISM OF REASONING. 129 

objects, a brain for example, can give us no infor- 
mation as to the forms of our tJiought, for it always 
implies them. Those who maintain the contrary- 
are guilty of di. petit io principii,* 

II. 

Thus extended and modified, the law of resem- 
blance will enable us to understand the genesis of 
external perception. Let us study this genesis in 
itself, without any preconceived ideas, without 
considering that the phenomenon is a result of 
reasoning. True to our method, let us appeal to 
pathology, for morbid cases often let us perceive 
the secret of the normal state. 

Hypnagogic hallucinations afford a wide field of 
observations and experiments. M. Maury hit upon 
the clever idea of making experiments on his OAvn 
person, so as to estimate to what extent external 
impressions intervened in dreams. In the evening, 
when he began to fall asleep in his arm-chair, he 
asked a person placed by his side to produce sensa- 
tions in him without forewarning him, then to 
awaken him when he had already had time to dream 
a dream. The results obtained by this method 
really belong to the study of external perception, 
for what is a dream when produced under these 
conditions? It is a cerebral reaction following an 
impression of the senses — and this definition applies 

*The same observations may be advanced in the case of those authors 
who, like Hamilton, Brochard, James, Rabier, etc., try, without introducing 

Ehysiology, to explain the resemblance between two states of consciousness 
y the common elements in the two states, or by a partial identity of their 
elements. This pretended attempt at simplification simplifies nothing at all, 
for it replaces the idea of resemblance by the ideas of identity and of unity, 
which are merely its derivatives. We repeat that resemblance is a single, 
ultimate and irreducible idea. (Cf. Brochard, De la lot de si7?iilarite, Revue 
philosophique, March, 1880.) 



130 THE PSrCHOLOGT OF REASONING. 

to perception. We shall presently see that the 
observer's dreams may be compared to artificial 
illusions of the senses. Here are the facts: 

His lips and the end of his nose are tickled with 
a feather; he dreams that he is undergoing a hor- 
rible torture, that a mask of wax is being placed on 
his face, then when it is being pulled off, the skin 
on his lips, nose and face is torn. A pair of tongs 
is rubbed with steel scissors a short distance from 
his ear; he dreams that he hears the sound of 
bells; this sound of bells soon becomes the tocsin; 
he thinks he is back in the days of June, 1848. 
He is made to breathe eau de cologne; he dreams 
that he is in a perfumer's shop, and the idea of 
perfume arouses that of the Orient; he is at Jean 
Farina's shop in Cairo. He is made to smell a 
burning match ; he dreams that he is at sea (the 
wind was then blowing on the windows) and that 
the Saint e-Barhe is pitching. He is pinched lightly 
on the neck ; he dreams that a blister is being 
placed there, which awakens the recollection of a 
doctor who attended him in his infancy. A warm 
iron is brought near to his face; he dreams of 
cJianffc2irs; the idea of these chauffeurs soon brings 
that of the Duchess d'Abrantes, whom he sup- 
poses in his dream to have taken him as her secre- 
tary. He had formerly read some details about 
cliaiiffeurs in the Memoirs of that clever woman, 
etc.* 

These experiments show that the qtiality of the 
sensory impression has an influence on the nature 

*Maury, So77i7neil et rives, p. 127. 



THE MECHANISM OF REASONING. 1 31 

of the dream, for the trace of the generating im- 
pression is found again in the images of fantasy. 

But some other observations by the same author 
may be here given which are still more to the 
point; they concern dreams produced by subjective 
sensations. One night, M. Maury, when half 
awake, sees a luminous spark (a subjective sensation 
of the sight); he immediately transforms it, yield- 
ing already to the desire for sleep, into a lighted 
street lamp. Then before his eyes appears the Rue 
Hautefeuille, lit by night, as he had many a time 
seen it when he was living in it, thirty years before. 
The following is another example from the same 
author: "When I suffer from retinal congestion, 
coloured patches and luminous circles shape them- 
selves upon my eye-lid. Well, in the short instants 
during which imaginary images foretell the coming 
of sleep, I have often found that the luminous 
image which was due to the excitation of the optic 
nerve was in some way altered under the eyes of 
my imagination, and became transformed into a 
countenance whose bright features represented those 
of a more or less imaginary person. It was possible 
for me to follow the metamorphoses effected by my 
mind on this original nervous impression, for several 
seconds, and I again perceived upon the forehead 
and cheeks of these heads, red, blue or green 
colour, a luminous brightness which shone before 
my closed eyes, previous to the commencement of 
the hypnagogic hallucination."* 

In many similar cases it may be found that the 

*0p. cit., p. 59. 



132 THE PSrCHOLOGT OF REASONING. 

imaginary image of the dream is preceded by phe- 
nomena of excitation, which are locahzed, perhaps 
wrongly, in the retina. The subject who is falling 
asleep begins by perceiving gleams, confused 
masses strewn with little coloured points, striae and 
filaments. The appearance of these amorphous 
sensations precedes the seeing of definite forms. 
M. Maury has expressed the idea that the dream 
hallucination arises from these "subjective spec- 
tres," and is derived from them by a kind of trans- 
formation. In this case there is, as M. Maury has 
correctly said, a met amor pilosis of images; and this 
metamorphosis recalls that of the zootrope. 

But in making this comparison we either say 
nothing at all, or we affirm a certain fact. We 
have seen how the change-effects produced by the 
zootrope are explained ; there is a series of impres- 
sions which follow each other at very short inter- 
vals; these impressions are not identical, no more 
are they absolutely different ; each resembles in part 
the one preceding and the one following it. By 
means of this partial identity each impression 
blends with its neighbour and forms with it a single 
whole. It is this fusion of successive impressions 
which gives the spectator the illusion of a single 
impression. We may suppose, in order to explain 
the genesis of the hypnagogic dream, that the 
principle of fusion operates not only between two 
sensations and between two images, but also 
between a sensation and an image. 

This supposition enables us to analyze the 
beginning of a hypnagogic hallucination in the fol- 



THE MECHANISM OF REASONING. 1 33 

lowing manner. A luminous sensation, a spark 
for example, crosses the field of vision ; this sensa- 
tion recalls, by the effect of resemblance, the mental 
image of an object which also presents a luminous 
point, for example the image of a lighted street 
lamp. Let us denote the initial sensation by the 
letter A, and the complex image of a lighted street 
lamp by the letters ABCDEFGH, etc. ; 
the letter A in the second group represents the 
luminous point in the lamp — that is to say, the ele- 
ment which is common to the image of the lamp 
and the sensation of a spark. But, further, the 
two elements represented by A fuse together and 
form a single element in such a way that the image 
evoked blends with the sensation, and the spark is 
transformed into a street lamp ; then this last image 
recalls the entire image of the street by the associa- 
tion of contiguity. 

We find this same fusion of sensations with 
images in a large number of toxic hallucinations. 
One woman who had just taken some hashish in 
order to experience the blissful delirium which that 
substance produces in the Orientals, "saw her 
brother's portrait, which was above the piano, 
become animated and display a forked pig-tail, 
entirely black," etc. A moment afterward she 
went towards the door of a neighbouring room which 
was not lit. "Then," she says, "I experienced a 
frightful thing; I was choked and suffocated; I fell 
into an immense bottomless pit, the well at Bicetre. 
Like a drowning man who clutches for safety at a 
frail straw which he sees escaping him, so I tried 



134 THE PSrCHOLOGT OF REASONING. 

to catch on to the stones which surrounded the 
pit; but they fell with me into that bottomless 
abyss." Her cries were heard, and she was 
brought back to the lighted part, and, her ideas 
changing with the new impressions, she thought 
she was at the opera ball, and she struck herself 
against a stool, which she took to be a masquerader, 
prone on the floor, and dancing in an unseemly 
fashion ; then she walked in the midst of a country 
of lanterns, which phantasmagoria was produced 
by the flame of the coals which burned in the fire- 
place.* When this sensory delirium is closely 
studied, its development may be readily followed. 
Its origin is in the sensations of every kind pro- 
duced by the external world in the midst of which 
the patient moves ; the impression of the senses calls 
up the images which resemble it ; these images 
appear, accumulate, become transformed under the 
influence of the toxic agent, become separated more 
and more from their point of origin, and finally 
create an entirely imaginary external world, which a 
new impulse of real sensations will again come to 
modify. But at the first moment of the evolution 
of the delirium, there is always at least a shade of 
resemblance between the exterior object and the 
images which it evokes, as is seen in the hallucina- 
tion of the well at Bicetre, produced by the dark 
room, and it is this resemblance which causes the 
fusion. 

Let us pass to the case of alcoholic delirium. 
We know that the visual hallucinations which 

*Moreau (de Tours), Du hachisch et de V alienation mentale, p. 14. 



THE MECHANISM OF REASONING. 135 

accompany it consist of terrifying visions of little 
animals, cats, rats, insects, spiders, human heads 
separated from their trunk, etc. These hallucina- 
tions are not formed at once ; according to the evi- 
dence of the best observers, the visions are preceded 
by elementary troubles of a purely sensory charac- 
ter. The patient sees black points or luminous 
spots, which are animated with rapid movement ; 
these are the subjective sensations from which the 
hallucination is formed, and which the brain of the 
alcoholic inebriate ere long transforms, according as 
the delirium becomes more accentuated. "In some 
cases," says Magnan, "the patient at first sees a 
dark, blackish spot, with a vague outline, then with 
distinct boundaries with prolongations which be- 
come legs and head, so as to form an animal, a rat, 
a cat, or a man." Does this phenomenon not 
recall the zootropic metamorphoses in a striking 
fashion? Is it not quite naturally explained by a 
fusion of sensations and images? 

The same explanation may be readily adapted 
to all cases in which our brain causes the sensations 
which it receives to undergo a transformation. One 
of the most interesting examples of such transform.a- 
tions is afforded us by what might be called imagi- 
nary perceptions. Everybody must have noticed that 
when the environment is favourable one can at will 
picture to oneself the presence of a certain body, 
and perceive it as if it actually existed. We distin- 
guish a great many forms in clouds, in rocks, in the 
confused masses of dim or distant objects, in the 
flames of a fire, in the inequalities of a wall, or in 



136 THE PSrCHOLOGT OF REASONING. 

the lines, holes and irregularities of a wooden table. 
It seems that Leonardo da Vinci recommended his 
pupils, when they were looking for a subject for a 
picture, to carefully study the appearance of sur- 
faces of wood ; in fact, at the end of a few minutes 
of attention, it does not take long to see certain 
animal forms, human heads, and sometimes whole 
scenes picturesquely arranged, shape themselves in 
the midst of the confused lines. On this matter I 
have a fairly extensive experience ; if I gaze attent- 
ively at a sheet of white paper, I always discover 
some figure on it; I can even copy it, and the 
drawings which I obtain by this process are gener- 
ally very superior to those which I am able to 
produce by imagination alone, although in reality 
they are not worth very much ; but this is a purely 
relative matter. I have often remarked that the 
figure is not formed right away, but slowly and by 
degrees, like a piece of decoration which is built up 
of successive pieces. The important thing is to 
obtain the first form ; if it is fairly vivid, it will not 
be long in completing itself, the edifice being 
noiselessly constructed on that first stone. 

It would be exceedingly interesting to study 
this imaginative side of our nature. The germ of a 
theory of invention, more genuine than all those 
which we have so far obtained, might perhaps 
indeed be found therein. However that may be, 
it is important for us to observe that the mind, in 
these perceptions, works on the fortuitous resem- 
blances which it discovers in an object ; it is through 
these points of resemblance that the imaginary 



THE MECHANISM OF REASONING. 137 

image is evoked and becomes blended with the sen- 
sible impression. At the same time, which is a 
curious thing, the mind systematically neglects all 
the characteristics of the external object which do 
not harmonize with this fiction. 

Imaginary perceptions belong to the same family 
as illusions of the senses; they might be defined 
as voluntary illusions. They are the dramas of 
which we are at once author and spectator. 
Involuntary illusions supply us with similar facts. 
Every time that an illusion lends itself to analysis, 
it is perceived that the false exteriorized image, 
which, properly speaking, constitutes the illusion, 
in some way resembles that which gave it birth. 
For example, when, by reason of distance or ob- 
scurity, we take one person for another, or allow 
ourselves to be deceived by an imperfect resem- 
blance, we commit an error of identification ; in 
other words, the first image awakened by the exter- 
nal sensations resembles them and is blended with 
them. This, moreover, is confirmed by hypnotic 
experiments. Move your hand before the eyes of 
a somnambulist, imitating the movement of wings 
with your fingers; he immediately sees a bird and 
tries to catch it. Imitate a reptile's movement with 
your hand on the ground, and he sees a serpent. 
The general rule is that the subject sees all the ob- 
jects whose appearance is simulated. 

We pass by an insensible transition from the 
illusion, or false perception, to true perception. 
Let us see if every act of perception likewise takes 
its rise in an act of identification. 



138 THE PSrCHOLOGT OF REASONING. 

I take hold of a book on a table; I lift it, open it, 
turn over its leaves, read it, and close it. All these 
acts have aroused a large number of impressions of 
touch, form, weight, temperature, resistance and 
movements in me, which are' united together and 
associated with the visual impressions which I .felt 
at the same time. Let us now suppose that I leave 
my room, and return to it after some minutes' 
absence. The book is still in the same place ; if I 
look at it, the visual impression which I experience 
awakens in my memory the images of sensations of. 
all kinds which I received when handling it a short 
time before. In short, images of touch, of the 
muscular and other senses proceed to combine with 
the visual sensation. Perception therefore takes 
place. 

But how does it L^ppen that this new visual 
sensation can awaken, under an ideal form, these 
impressions formerly received by the hand? There 
is in this case no bond of resemblance, nor even 
any bond of contiguity, for the actual sensation of 
sight is absolutely new, arid could not become asso- 
ciated with impressions received by the hand several 
minutes before. There is one reply, and only one, 
to this question ; it is that the actual aspect of the 
book resembles in part or in totality the former 
aspect, the recollection of which persists in my 
mind. From my preceding experience there sur- 
vives an ocular image of the book, associated with 
impressions from the hand. The appearance of the 
book as actually seen is fused with this visual recol- 
lection, which in its turn brings the train of tactile 



THE MECHANISM OF REASONING. 1 39 

and muscular recollections to which it is bound 
into the field of consciousness. 

According to this interpretation, the series of 
states of consciousness which succeed each other in 
perception is as follows : 

The actual vision of the book (A) excites in our 
thought, by the force of similarity, the ocular image 
of the same book (B) which is due to a former 
vision, and this second state of consciousness in 
its turn excites, by the force of contiguity, the 
group of tactile and muscular impressions (C). It 
is the state of consciousness (B) which enables the 
first state to excite the third ; so I propose to call it 
the intermediate state of conseiousness, in order to 
express its function. 

The curious fact is that this image (B), the 
visual recollection of the uuok, does not make its 
appearance, in spite of the importance of the part it 
plays. When we look at the book, we do not have, 
simultaneously with this vision, the distinct recol- 
lection of a former vision. Yet this recollection 
constitutes an indispensable part of the operation, 
for without it perception would be impossible ; it is 
in a manner 'invisible and present;" it is fused 
with the visual sensation of the moment, and be- 
comes one with it,* so that this sensation is found 
directly associated with the group of tactile and 
muscular images. 

Let us represent the course of the phenomenon 
graphically. 

*We assume, for the sake of simplicity, that the actual vision of the 
book and the visual recollection of the same object completely resemble each 
other, and that the fusion is total; if the resemblance is only partial, the 
fusion also is partial. 



140 THE PSrCHOLOGY OF REASONING. 

The perception of the book has the effect of 
uniting a visual sensation to a group of tactile and 
muscular images. The formation of this associa- 
tion constitutes the conclusion of the perceptive 
reasoning. This mental synthesis may be expressed 
by the formula 

A-C 

in which A represents the actual vision of the 
book, C the group of muscular and tactile images 
— that is to say, the fact inferred, and the sign — 
the bond of association which unites these two 
terms.* 

The psychological question which now arises is, 
as we have shown above, to explain the formation 
of this association. Now, we say that the actual 
vision of the object begins by reminding us of a 
former vision by means of the resemblance between 
these two states. This again m-ay be represented 
symbolically in the following manner: 

A:=B 

In this formula A continues to represent the 
actual vision of the book placed before our eyes, B 
represents the recollection of a former vision of that 
same book — that is to say, its visual image — and 
the sign = indicates the resemblance between the 
sensation and the image. This identification is, in 

*We employ algebraic signs merely in order to represent in a graphic 
manner the properties of the images which cooperate in an act of reasoning. 
It must be added that in no way do we place ourselves at the point of view of 
English logicians such as De Morgan, Boole, and Stanley Jevons, who also 
make use of these signs, but for the purpose of putting the problem of logic 
in the form of an equation, and of solving it by processes more or less analo- 
gous to those of algebra. Consult on this subject the interesting work of 
Louis Liard, Les logiciens anglais confemporains.) 



THE MECHANISM OF REASONING. 14I 

our opinion, the first part, the first act of external 
perception. 

In this case there is not only a recollection, a 
calling up of the image B, but this image, when 
once evoked, becomes fused with the sensation A, 
like the two sensations of the points of the com- 
passes in Weber's experiment. There is nothing 
astonishing in this result if we recollect that an 
image is almost a sensation. We have devoted a 
chapter to demonstrating that fact. We may there- 
fore indicate this fusion in the following manner, 
which has the advantage of appealing to the eye: 

[A=B] 

In this new formula the brackets express the 
fusion of the sensation and the image. 

Here the first act of perception finishes and the 
second begins. We have assumed in our example 
that former experiences had cemented an associa- 
tion between the vision of the book and the exceed- 
ingly diverse sensations which this object produces 
when we take it up, open it and read it, sensations 
the recollection of which has been designated by 
the letter C. This may be represented thus: 

B-C 

a formula in which B still represents the former 
vision of the book, C the experiences of active 
touch, and the sign — the pre-formed association 
between these two images. 

We therefore say that, through the fact of the 
fusion of A and B — that is to say, in consequence 



142 THE PSrCHOLOGT OF liEASONING. 

of the fusion of the actual vision with the visual 
recollection of the object — C is associated directly 
with A, or, in other words, the idea of the invisible 
attributes of the object is directly associated in our 
mind with its visual aspect. Finally, we arrive at 
this last formula, which is self-explanatory : 

[A = B]-C 

To sum up, the whole operation may be analyzed 
thus: An association by resemblance, the purpose 
of which is to introduce an association by contiguity. 
As the latter is the end, it diverts the attention 
from the former, which is the means. 

It would be easy to simplify the description of 
this operation by showing that it may be reduced 
to the partial assimilation of two images. In fact, 
perception is produced by the partial fusion of the 
ocular sensation which the object actually produces 
upon us with the complete recollection of the same 
object, or of a similar object, which lives in our 
memory. This assimilation of two impressions is 
the biological property from which reasoning 
springs. 

We began by offering this mechanism of percep- 
tion as a hypothesis. But if this explanation be 
compared with all the pathological facts which have 
been cited, it will be recognized that the hypothesis 
very nearly attains to the rank of theory. We have 
seen that in all the morbid perceptions which lend 
themselves to analysis, the phenomenon begins with 
an act of identification — that is to say, by z. fusion 
of the excitative sensation with the first image wJiicJi 



THE MECHANISM OF REASONING. 143 

it evokes. We may recall, among the most typical 
cases, the sleeper who, seeing a spark, transforms it 
into a lighted street-lamp, and sees a street lit at 
night appearing before him ; the alcoholic inebriate 
who, seeing black points moving in his field of 
vision, transforms them into little black beasts with 
lengthening legs; the wide-awake person who, by 
fixing his attention on the confused lines on a table, 
finishes by seeing fixed forms come out of them ; 
and, finally, the individual affected by an illusion of 
the senses, who confounds a stranger with a friend, 
letting himself be deceived by a rough resemblance 
of size, of figure, or of dress. Always and every- 
where external perception, whether it be exact, 
whether it be false (illusion), or whether it be insane 
(hallucination), takes its rise in a fusion between the 
sensations of the external world and the images 
which these sensations cause to spring up in the 
mind. 

The only difference is that in false and patholog- 
ical perceptions a shade of resemblance is sufficient 
to produce suggestion, while in correct perception 
we only take account of an ensemble of resem- 
blances, and even a shade of difference is enough to 
prevent suggestion. Helmholtz has remarked that 
in the stereoscopic arrangement the presence of a 
badly-projected shadow destroys the illusion. But 
we are obliged, in the interests of clearness, to put 
aside these details. All that we retain of the pre- 
ceding discussion is the fact that perception takes 
its rise in identification. 

Moreover, how could it be otherwise? When 



144 THE PSrCHOLOGT OF REASONING. 

we perceive an external object, we receive sensa- 
tions which are always new and distinct from all 
those which have preceded them. How then could 
those new sensations evoke past, former states, 
such as images, if not by the effect of resemblance? 
Resemblance is the only bond which could unite 
states separated by time. Let us state this problem 
in an a priori form, employing the formulae which 
we have already made use of. On the one hand, B 
is associated with C. On the other hand, A resem- 
bles B. How can A become associated with C, if 
not through the medium of B? 

Before going further, we wish to show that these 
complex phenomena in which similarity and con- 
tiguity are combined have already been noticed by 
psychologists, although they did not understand 
their significance. Two passages may be read in 
this connection, one from James Mill {A?ialysis of 
the Phenomena of the Hiunan Mind, Vol. I, p. in, 
et seg.), and the other from Mr. Bain (eod. loc, p. 
464, et seg.). We shall quote only Mr. Sully, who 
remarks, in his book, entitled Ontlines of Psy- 
chology, that the two laws of . contiguity and simil- 
arity are at once distinct and inseparable. "Each 
mode of reproduction may be said to involve the 
cooperation, in different proportions, or with differ- 
ent degrees of distinctness, of two elements, a link 
of similarity or identity and a link of contiguity. 
Thus when a person's name calls up the image of 
his face, it is because the present sound is automat- 
ically identified with previously heard sounds. So, 
too, revival by similarity commonly involves con- 



THE MECHANISM OF REASONING. 1 45 

tiguity as shown above. But in ordinary cases 
what we call revival by similarity involves the call- 
ing up of concomitant circumstances." The author 
symbolizes the relation between the two laws as fol- 
lows: 

A A 

Contiguity Similarity 

(a) — 71 c — (a) — f . 

In the first case the process of identification be- 
tween A and (a) is automatic or unconscious, and 
the revived concomitants {jt) are thought of as quite 
distinct from that which revives them ; whereas in 
the second case the identification is the important 
step in the process, and the concomitants (c and f) 
are not distinctly separated from the identified 
element (a). We have only to compare this plan 
with our own to recognize the identity of the two : 
First of all we see therein the fusion of one state of 
consciousness with a second similar state, then the 
suggestion of a third state which was associated with 
the second by contiguity. 

But what is yet more important to notice is that 
the process of perception which we have described 
is, according to Stuart Mill, Mr. Bain and Mr. 
Sully, a general process, which is realized every 
time that an association of ideas comes into play — 
that is to say, at every instant in our lives. Now, 
as we shall presently proceed to demonstrate the 
logical value of this process, which constitutes true 
reasoning, we shall consider reasoning, not as an 
accidental fact, but as the constant element in our 



146 THE PSrCHOLOGT OF REASONING. 

lives, the fabric of all our thoughts. Thus, we shall 
come to accept as a demonstrated truth that appar- 
ent paradox of Wundt's : The mind might be defined 
as a tiling which reasons. 

III. 

The phenomena which we are at present study- 
ing are so important that we are willing to protract 
the examination. Perception, we have said, is an 
operation in three terms; we have seen how many 
proofs lend support to this proposition. But we 
wish to continue the demonstration to its conclusion 
by quoting examples of perceptions in which the 
distinct existence of these three terms may be 
directly recognized by inspection alone. This 
occurs whenever perception, in evolving and becom- 
ing complicated, tends to become confused with 
conscious and voluntary reasonings. 

Let us take a simple example, which we shall 
afterwards try to complicate. In what does the 
process of reading a written word consist? At first 
sight it is merely bringing an association of con- 
tiguity between a graphic sign and an idea into 
operation. When the graphic sign is very clear, 
like a printed letter, the suggestion of the image 
follows the seeing of the sign immediately; the 
operation appears to be in two terms, like the ma- 
jority of our ordinary perceptions. For example, 
the image of a house appears vaguely when we read 
the word ' ' house. ' ' But let us complicate the opera- 
tion a little ; let us try to retard it in order to grasp 
it better in detail, and a supplementary term is im- 



THE MECHANISM OF REASONING. 147 

mediately detached. We take, in place of a printed 
word, a word written by the hand and almost 
illegible. Then we perceive that the sight of the 
characters is not enough to make them understood; 
it is necessary, in addition, to recognize them, to 
state that this disfigured letter is an «, this other a 
c, and so on. But how is this recognition possible, 
if not by a comparison between the altered character 
and the recollection of the normal character? We 
decide that this letter is an a by ascertaining that it 
more or less resembles the letter a which we know. 
Eliminate this recollection, this intermediate state 
of consciousness, and the operation becomes impos- 
sible. 

There are numerous examples of the same kind. 
One more may be given. There are some diag- 
noses which are made at a distance, so far as they 
are easy ; a neuro-pathologist has often merely to see 
a sufferer from ataxia walking, or a paralytic (Park- 
inson's disease) moving in the street in order to 
recognize their disease. The mere sight of a prom- 
inent symptom evokes the name of the disease, and 
the representation of all the other symptoms which 
belong to the same affection. But most frequently 
the sight and even the methodical examination of 
the patients is not enough; the physician must 
gather his recollections together in order to make 
the diagnosis. What does he do then? He com- 
pares the case he has before him with analogous 
cases which have already occurred. Trousseau 
even said that in this work of comparison he dis- 
tinctly remembered patients whom he had formerly 



148 THE PSrCHOLOGT OF REASONING. 

seen in the hospital while he was a student; he 
pictured their appearance, and even, he says, the 
number of their bed. This conscious reversion to 
previous and similar cases brings the intermediate 
state of consciousness prominently into view. This 
state is always apparent when the similarity does 
not operate in a sure and infallible manner. 

We may therefore affirm that three images suc- 
ceed each other in the perception of an external 
object. We have still to show the importance of 
this analysis. It is exact, it may be said, but what 
is the use of it? It describes for describing's sake; 
it supplies no information as to the mechanism of 
reasoning; after having engaged in a minute psy- 
chological dissection, we know no more of the mat- 
ter than we did before. 

Our aim is to show briefly, and above all as 
clearly as possible, the significance of the results 
obtained. We are convinced that we are now able 
to give an exact theory of the mechanism of reason- 
ing; in fact, thanks to this supposition that in every 
perception there exists an intennediate state of con- 
sciousness (B), serving as the connecting link be- 
tween the impression of the senses (A) and the 
inferred images (C), everything becomes clear; this 
supposition is like the word which, interpolated in 
a mutilated text, reveals its meaning. We shall 
presently see that we can recognize, in the account 
of perception reconstituted in this manner, all the 
parts which go to form a regular act of reasoning. 

First of all, the act of perception becomes a 
transition from the known to the unknown by 



THE MECHANISM OF REASONING. 149 

means of a resemblance, and it will be remembered 
that this is a rough, though exact, definition of 
reasoning. The known fact is the sensation which 
we actually experience, for example, the visual 
sensation of a book placed on a table. The un- 
known fact is the nature of the object which gives 
us this visual sensation. We obtain this desired 
idea through the suggestion of a recollection — the 
image of a book ; now, the transition from the sen- 
sation to the image, from the known fact to the 
unknown fact, is afforded us by the resemblance 
of the visual object to the object with which we 
identify it. 

It will perhaps be said that reasoning is some- 
thing more than this consecution of images ; it is a 
judgment, it is the formation of a new belief. 
Therefore it is not sufTficient to explain how the 
complete and detailed image of the book can be 
called forth on account of an elementary sensation 
of sight or of touch ; it would still be necessary to 
give an account of this new belief which enables us 
to affirm that "this is a book." The suggestion of 
a fact is one thing, and the judgment which accepts 
it as true is another. For example, we shall not 
explain the reasoning v/hich makes us say that Paul 
is mortal, if we merely show how the idea of the 
death of this individual comes to our mind; as we 
may yet state how this idea determines our convic- 
tion. Such is the objection which certain readers 
will not fail to offer. Let us try to reply to it. 

Belief, conviction and assent are among those 
vague, liquescent and ill-defined phenomena which are 



150 THE PSYCHOLOG7' OF REASONING. 

numerous in psychology; they could with difficulty 
be made the subject of methodical study. But 
psychologists have adopted a bias; they have 
remarked that belief generally resulted from a rela- 
tion between images. When two facts have often 
occurred at the same time or in immediate succes- 
sion, the corresponding images have a tendency to 
become connected in our mind, and, further, we 
have a tendency to believe that the phenomena, 
the ideas of which are associated in our mind, are 
likewise associated in reality. (See p. 79.) This 
stated, it is clear that a theory will explain the 
formation of a new belief if it explains not only the 
suggestion of the idea to be affirmed, but the asso- 
ciation, the organization of this idea with others. 
Let us repeat our argument, so as to make it clearer. 
We admit that it is not sufficient to say, in order to 
explain our reasoned conviction that a certain man 
must die, how we obtain the idea of the death of a 
man ; but the moment we explain how this idea of 
death becomes associated with that of the individual 
in question, so as to produce the belief that he is 
mortal, we have attained our end, and demonstrated 
that which required demonstration. 

Well, has this demonstration been furnished? 
Has the preceding analysis explained how, apart 
from all experience, merely by an operation of 
mental laws, an association can be formed between 
two images? This was, it will be remembered, one 
of the conditions which we had urged (p. 94) 
against every explanation of reasoning — this condi- 
tion seems to us to be fulfilled. We have seen the 



THE MECHANISM OF REASONING. 15 1 

reason why the detailed image of the book is com- 
bined with the visual sensation of the moment ; it is 
because these two impressions have points of resem- 
blance which weld them together. Thus are ex- 
plained all the syntheses of our sensations and of 
our recollections. 

But that is not all ; a reasoned conclusion does 
not merely include an adoption of a new truth. 
This truth also presents that particular character of 
being a logical consequence of a truth already 
admitted. In psychological terms the association 
of images which is established by reasoning takes 
place through the medium of preexisting associa- 
tions which are called premisses. To reason is to 
establish associations on the model of other associ- 
ations which are already formed. (See p. 95.) It 
remains to show that our thesis on the mechanism 
of perception gives an account of this latter charac- 
ter of reasoning. To this end, we must establish a 
new parallel between external perception and the 
syllogism. . 

In the first place, it will be observed that per- 
ception is an operation in three terms, A, B, C. 
The first term (A) represents the actual vision of the 
object, the second (B) its former vision, and the 
third (C) the inferred properties. The syllogism is 
also an operation in three terms; in the example 
which we analyzed before, these terms are Socrates, 
man and mortal. 

Again, in the syllogism the mean term enters 
into the major and the minor and disappears in the 
conclusion, although it is preparatory to it. It is 



152 THE PSrCIIOLOGT OF REASONING. 

the term "man." Reasoning, as Boole remarks, 
is the elimination of a mean term in a system of 
three terms. This mean term, we say, is prepara- 
tory to the conclusion ; for if Socrates were not a 
man, he would not be mortal. Similarly in percep- 
tion, the term B, the visual recollection of the 
object, is a true mean term ; on the one hand, it 
vanishes when we reach the conclusion, for it blends 
with the actual vision (A) ; on the other hand, it is 
preparatory to the conclusion, for if the actual aspect 
of the object did not resemble the former aspect 
already seen (B), we would not be able to recog- 
nize it. 

But the parallel may be pushed much further. 
It is possible to divide the act of perception into 
three slices, as is done with the syllogism — that is 
to say, into three parts which correspond to the 
three verbal propositions of an act of logical reason- 
ing. 

Let us begin by translating the familiar syllo- 
gism, which we have used so often, into psychological 
language. Let us take the major premiss first: 
A II men are mortal . 

This proposition states, according to a logician's 
analysis,* that the attributes connoted by "man" 
never exist unless conjoined with the attribute 
called mortality, so that wherever the first attribute 
is found we may be sure of the existence of the 
second. It is a relation between two facts. Psy- 
chologically, the proposition has another meaning; 
it means that there exists in our mind an associa- 

*John Stuart Mill, Logic, p. 122. 



THE MECHANISM OF REASONING. 153 

tion between two groups of images, one group of 
abstract images representing man, and one group of 
generic images representing death. We understand 
by the word association that these two images are 
produced simultaneously or in immediate succession 
in our mind. We say again that the two images 
are contiguous. Consequently we shall call our 
major proposition a proposition of contiguity. It 
is to our past experience, or to the testimony of 
others, that we owe that association ; it is given, 
acquired, considered as corect, at the moment when 
we perform the act of reasoning. It is upon it that 
our conclusion will depend. 

The minor premiss of the reasoning 
Socrates is a man, 
is of another nature. It signifies from the 
logical point of view that there is a perfect resem- 
blance, an identity, between certain attributes of 
Socrates (colour, form, size, internal structure) and 
the attributes of humanity. That is what the 
proposition signifies; now, as a distinct question, 
what is it from the psychological point of view? It 
is an act of assimilation between the image of cer- 
tain attributes of Socrates and the generic image of 
humanity. Here the mind seizes a resemblance 
between two groups of images, and the proposition 
which expresses this internal act may be called a 
proposition of resemblance. 

The conclusion 

Socrates is mortal, 
contains the truth discovered by deduction. Con- 
sidered from the objective point of view, it signifies 



154 ^^HE PSYCHOLOGl' OF REASONING. 

that there exists a relation of coexistence between 
the individual called Socrates and the attributes of 
mortality, or, in other words, that Socrates pos- 
sesses these attributes. Psychologically, this prop- 
osition indicates that a relation of contiguity has 
been established in our mind between the image of 
Socrates and the image of mortality. 

To sum up, the preceding reasoning may be 
divided into three propositions: (i) A proposition 
of coexistence, the major premiss; (2) a proposition 
of resemblance, the minor premiss ; (3) a proposi- 
tion of coexistence, the conclusion.* 

Now, let us put the propositions of the syllogism, 
on the one hand, opposite the symbolic formulae 
which we employed in our analysis of perception, 
on the other hand : 

Major premiss: All ineji are mortal B— C 
Minor premiss: Socrates is a man A=B 
Conclusion: Socrates is mortal (A=B) — C 

The major premiss of our syllogism is, we have 
said, a proposition of coexistence; it signifies that 
the generic image of man is associated in our mind 
with the abstract image of iriortality. Similarly, in 
the formula B — C we find an association of images 
indicated ; for this formula means that the former 

*Arrnrdinff to Mill {of. cit., p. 123;, the principle involved in every 
inference strikfng?y resembles the"^ axioms of mathematics. It is that 
•^things whixhcolxlst with the same thing, coex st with one another.' Thus: 
Sorratps coexists with man-Mortality coexists with man.-Therefore 
Socra el and mortal ty coexist with one another. But there is an error in 
tl?fs analysis- ?n reality the reasoning is not composed of three propositions 
o coeKistei ce The minor premiss is a proposition of resemblance. To say 
that Socrates is a man mea£s that he resembles men whom we know. Mill 
him..plfremarks this (p ^Ss). So we ought rather to say:-Socrates resembles 
mi^L-imn coexists wi^th^^ coexists w th mortality. If 1 

were dTsl^ed tha? a p inciple should be deduced from tn.s operation at all 
rnsts we would propose the following: "A thing which resembes anothe. 
thing coinmunicates to it the property which it has of coexisting with a 
third." 



THE MECHANISM OF REASONING. 155 

vision of the book (B) is associated with the image 
of its tangible quahties (C). Therefore, on both 
sides there is the same association of contiguity. 

The minor premiss of our syllogism expresses a 
resemblance between the mental representation of 
Socrates and that of the attributes connoted by the 
word humanity. In the formula A = B, there is also 
an identification between the actual vision of the 
book (A) and the recollection of a former vision (B) 
— that is to say, between the sensation and the 
image of one and the samie thing. Therefore, on 
both sides there is the same association of resem- 
blance. 

Finally, the conclusion of our syllogism indicates 
that an association of contiguity exists between the 
image of Socrates and the image of death. In the 
formula (A=B) — C, we also see an association of 
contiguity become formed between the vision of the 
book and the idea of its tangible attributes. There- 
fore, there is, once more on both sides, the same 
association of contiguity. 

It would be superfluous to dwell further on this 
matter. Perception is evidently composed of the 
same parts as formal reasoning. But the direct 
study of form.al reasoning cannot lead to a theory 
of that operation, for the states of consciousness 
which are its subject are too complicated for one to 
be able to observe the law according to which they 
are connected. When I say, "All men are mortal; 
Socrates is a man, therefore he is mortal," what 
takes place in my mind? Of that I know nothing 
accurately. I seem to perceive a train of confused 



156 THE PSTCHOLOGT OF REASONING. 

images. In any case I am unable to understand how 
these images are connected and disposed in reasoning. 
I am, to employ one of Wundt's comparisons, like a 
physicist who wished to study the vibrations of a 
pendulum by looking at them through a keyhole, 
or like an astronomer who, to study the sky, took 
up his residence in a cellar. 

The study of simple perceptions reveals to us the 
law we seek ; it shows us that sensations and images 
become organized by virtue of the two laws of sim- 
ilarity and of contiguity. The study of morbid 
cases, dreams, hallucinations, etc., throws full light 
upon the subject. 

Finally, our theory satisfies the three conditions 
which we had laid down ; it introduces only the 
known laws of the association of images ; it explains 
how an association is established between two 
images by the operation of mental laws alone; 
finally, it explains how that association is formed 
on the model of former associations. 

All the preceding discussion may be reduced 
to a single formula, which will serve us as a defini- 
tion: 

Reasoning is the establisJiment of an association between 
two states of cofiscionsness, by means of an intermediate 
state of consciousness which resembles the first state, 
which is associated with the second, and which, by fusing 
itself with the first, associates it with the second. 

It is often convenient to characterize a theory in 
a word. Our theory of reasoning is a theory of 
substitution. We see in it the main term (A) sub- 



THE MECHANISM OF REASONING. 157 

stituting itself for the middle term (B) — that is to 
say, one image taking the place of another and 
partially identical image.* 

*We have had the pleasure of meeting a very analogous theory in an 
article signed by a very keen and original psychologist, Mr. William James. 
After having defined similarity as tiie association of wholes, or aggregates 
by virtue of their common points, he observes that the process of association 
by similarity closely resembles that of reasoning properly so called. Reason- 
ing, says he again, consists in a substitution of parts of different wholes. In 
a certam sense it would be not at all too paradoxical to say that confusion 
and reasoning are two species of the same genus. We identify the thing in 
question with a part of a certain other whole. In this common process, if the 
operation be exact, there is reasoning; if not there is confusion. — We quote 
from M. Renouvier's analysis. {Critique philosophiqtie, 1879, p.S7o et seq.) 



CHAPTER V. 

CONCLUSION. 



We consider it useful to distinguish carefully 
between the results of our analysis and the conclu- 
sions which we shall presently draw therefrom. 
We believe it will be readily admitted that in every 
perception there exists a succession of three images, 
the first of which fuses with the second, which in 
its turn suggests the third. The existence of these 
three images and their coordination appears to be 
now and heretofore well established. These are 
facts which psychologists of any school may admit 
without fear of compromising the theories that are 
dear to them. 

But the conclusions, the interpretations which 
these facts suggest, will not, in all probability, meet 
with so ready an assent, for I shall presently have 
to touch upon questions on which many minds are 
already decided. It is only right to add that these 
interpretations are much less solidly established 
than their point of departure. 

Under cover of these reservations I shall try to 
show that the theory of tJirec images is applicable 
to reasonings of every kind, and therefore consti- 
tutes a general theory of reasoning. We might 
already afifirm, a priori, the legitimacy of this 

I c8 



CONCLUSION. 159 

investigation ; for unless it be maintained that 
higher reasoning has been created in its entirety, it 
must certainly be admitted that it is the termina- 
tion of an ascending evolution, and we must indicate 
from what lower form it proceeds. 

The reader already knows that there is no de- 
cided difference between perception and logical 
reasoning; the two operations are both reasonings, 
transitions from the known to the unknown. The 
analogy is so close that we were able to compare 
perception with formal reasoning, and to show that 
perception contains all the essential elements of a 
peripatetic syllogism. (See p. 88.) In short, per- 
ception and logical reasoning are only the two 
extremes of a long series of phenomena, and when 
we place ourselves in the middle of the series we 
find inferences which belong to both at the same 
time. (See p. 70.) Further, we have shown that a 
kind of filial relationship exists between perception 
and the reasonings of conscious logic. Thus, when 
we make systematized anaesthesia, which has been 
developed in a patient relatively to a certain person, 
gradually disappear, the thing which appears first of 
all is the perception of the person as species ; and 
it is only afterwards, by a kind of ascending evolu- 
tion, that the recognition of the person as individ- 
ual takes place ; now, we know that recognition is 
a complex operation Avhich touches closely upon 
reasoning properly so called. All these reasons 
lead to the belief that perceptive reasoning and 
logical reasoning imply the same mechanism, (See 
P- 77-) 



l6o THE PSrCHOLOGT OF REASONING. 

Let us now examine the principal objections 
which may be made to this argument. 

One of the characteristics which distinguish 
logical reasoning from perception is that objects 
constitute the material of logical reasoning and 
sensations the material of perceptive reasoning. 
There follows from this a second difference, drawn 
from the existence of language ; language being 
formed in order to name objects and not sensations, 
lends its support to logical reasoning and refuses 
it to perception. But let us neglect this second 
difference, which is secondary and derivative, so as 
to devote our attention to the first. Let us be 
exact. In what, from the psychical point of view, 
do the terms of logical reasonings consist? Some 
consist of general and abstract ideas; the others are 
recollections of facts, or recollections of particular 
objects. All of them are the residues of former 
perceptions; they proceed from them more or less 
directly, but they all do proceed from them; they 
are all percepts. 

Up to the present we have considered the percept 
as a synthesis of sensations and images, or rather 
as a sort of microcosm; here the percept becomes 
unity. We may compare it to a chemical radicle, 
which, although composed of atoms of different 
bodies, reacts like a simple body. The percept of 
a person or of a fact, in which we saw the result of 
automatic reasoning, becomes a term in complicated 
reasonings ; so that we might say of these latter 
operations that therein we reason on reasonings. 

This stated, the question is to know whether 



CONCLUSION. l6l 

logical reasoning is constructed with percepts as the 
percept is constructed with sensations. No good 
reason can be alleged against this unity of mental 
composition ; we do not see why percepts, which 
are groups of images, should have other properties 
than isolated images and sensations ; and we do 
not see why the percepts of logical reasoning should 
not associate themselves according to the same 
processes as the images and sensations in automatic 
reasoning. 

To make ourselves better understood, let us 
appeal to an analogy. When we wish to prove 
that a visual recollection produces the same chro- 
matic effects as the actual vision, we experiment 
with the most simple visual recollection, the repre- 
sentation of a colour; we have seen elsewhere 
(p. 40) that the idea of that colour, of red, 
for example, produces a consecutive green image. 
The experiment only succeeds by placing one's 
self under such conditions of simplicity; no 
consecutive coloured sensation would be obtained 
by mentally representing to one's self a com- 
plicated object, such as a country landscape or 
the appearance of a market. Nevertheless, we cer- 
tainly do not hesitate to transfer to the complex 
image the phenomenon observed in the simple 
image of a colour, and to make this phenomenon a 
general property of images. We believe that the 
generalization is quite as legitimate in the case of 
reasoning; we claim that in this case again, what 
can scarcely be ascertained directly save for isolated 
images should be transferred to complex images; 



1 63 THE PSYCHOLOGT OF REASONING. 

we claim that it should be admitted that the terms 
of logical reasoning are connected in accordance 
with the same laws as the images of perceptive 
reasoning, because these terms are groups of images 
which should have the same properties as isolated 
images. 

But there is a still more decisive reason for be- 
lieving that logical reasoning is constructed on the 
same model as perception. Our analysis of percep- 
tion took the study of the syllogism as its point of 
departure; it was proposed as an aim to find in 
perception again all the parts of which formal rea- 
soning is composed; this method led us to discover 
three terms and three propositions in perception, 
comparable in all respects to the terms and the 
propositions of the syllogism. From that dissection 
resulted the theory of three images. Why should 
this theory not be applicable with entire justice to 
the syllogism, since it comes from it? 

We shall conclude with some reflections on the 
order in which the syllogistic propositions are 

arranged. 

Mr. Spencer has directed a certain number of 
critcisms against the syllogism in this connection, 
some of which appear to us to be well founded. 
"When I say," he says,'^ 

''All crystals have planes of cleavage; 

' ' T/ns is a crystal; 

''Therefore, this lias a plane of cleavage; 
and when it is asserted that this describes the 
mental process by which I reached the conclusion, 

*0/. at.. Vol. II. p. 97- 



CONCLUSION. 163 

there arises the question, What induced me to 
think of 'all crystals'? Did the concept 'all 
crystals' come into my mind by a happy accident 
the moment before I was about to draw an infer- 
ence respecting a particular crystal? No one will 
assert such an absurdity. It must have been, then, 
that a consciousness of the particular crystal identi- 
fied by me as such was antecedent to my concep- 
tion of 'all crystals.' " That is, one of the elements 
of the minor premiss has suggested one of the 
general elements of the major premiss. This 
objection seems to us very reasonable, as it leads 
us to transpose the premisses in the following way: 

This is a crystal; 

All crystals have planes of cleavage; 

This has a plane of cleavage. 

But we are quite unable to follow Mr. Spencer 
in his objections to this new arrangement of the 
premisses. Why, he asks, have I been led by the 
idea of this particular crystal to think of all crys- 
tals, and not of quite another class? Why? we 
may answer. It is in consequence of a relation of 
resemblance; it is because "this" resembles a crys- 
tal, crystals which we know, and consequently the 
class of crystals. Why, says Mr. Spencer again, 
when I think of crystals do I think of their planes 
of cleavage, and not of their angles, their axes, or 
of any other of their properties? I think of their 
planes of cleavage by reason of a pre-established 
relation of coexistence between crystals and planes 
of cleavage. I would have been able to think of 
any other attribute, it is true ; in that case the 



164 



THE PSrCHOLOGT OF REASONING. 



conclusion would have been different, and instead 
of saying that this crystal has a plane of cleavage, I 
would have attributed to it a certain other property. 
That is all. Is a thing impossible because it would 
have been possible otherwise? 

It is therefore necessary in every syllogism to 
transpose the premisses, to place the minor before 
the major, and to say: "This is a crystal; all crys- 
tals have planes of cleavage, this has a plane of 
cleavage;" or again, "Socrates is a man; all men 
are mortal, therefore Socrates is mortal." 

We then discover a striking resemblance be- 
tween perceptive reasoning and logical reasoning. 
In the two cases, the operation begins in an asso- 
ciation of resemblance. The new arrangement of 
the syllogistic propositions is therefore quite con- 
formable to the course which the mind follows in 
reasoning, since it reproduces the course of percep- 
tive reasoning, that which constitutes the true "liv- 
ing" reasoning, while the reasonings of logical 
treatises are dead reasonings, dissected by the 
logicians.* 

*Thus we believe that, in all kinds of reasoning, the psychical labour 
consists essentially of a fusion of images. But this conclusion in no way 
prevents us from recognising that the human mind passed over an immense 
interval on the day when it passed from perceptive and unconscious reason- 
ing, which is common to the majority of animals, to logical, conscious, really 
scientific reasonings, which are only accessible to a very small number of 
individuals. The superiority of these latter reasonings depends upon an 
infinity of causes; they imply the power of seizing, beneath apparent con- 
trasts, real similitudes (for example, the assimilation of the mechanical force 
of the wind with that of a waterfall, of the flower with a transformed leaf, of 
the skull with a vertebra, of the lightning with the electric spark, of respira- 
tion with combustion, etc.); they imply a comparison between the various 
parts of reasoning, which are all brought before the mind, and which permit 
it to judge if the conclusion is justified by its premisses; finally, they have 
the result not only of demonstrating, but of explaining, by bringing the 
inferred fact back under a more general law; in this lies the superiority of 
reasoning over observation, of the deductive sciences over the experimental 
sciences, of the geometry of Euclid over tachimetry. 



CONCLUSION. 165 

II. 

Let us admit that reasoning is essentially one, 
that the simplest of inferences is, like the highest 
of generalizations, produced by a fusion and a 
grouping of images. From this general definition 
of reasoning we may deduce its utility, its function, 
its sphere and its limits. If it be recollected that 
images are fragments, residues of former sensa- 
tions; that they spring from the same place as for- 
mer sensations have been received, in the sensory 
centres of the cerebral surface layers; it will be 
understood that the purpose of these images, in 
grouping themselves in reasonings, according to the 
laws of their affinity, is to replace the absent sensa- 
tions. 

Such is therefore the function of reasoning; it 
enlarges the sphere of our sensibility, and extends 
it to all objects which our senses cannot know 
directly. Thus understood, reasoning is a supple- 
mentary sense, which has the advantage of being 
freed from those strict conditions of time and space, 
the two enemies of human knowledge. Reasoning 
is in turn the eye which sees, the hand which 
touches and the ear which hears. 

We find examples of these different functions in 
the study of perceptions. 

When, during the night, we cross a room which 
we know, the impressions of touch which we feel 
excite visual images which guide us among the 
furniture and prevent our striking ourselves and 
stumbling. The mechanism of this suggestion is a 



1 66 THE PSrCHOLOGT OF REASONING. 

perception of touch — that is to say, a reasoning. 
Reasoning therefore enables us in a manner to 
see, by means of the visual image, the object which 
we touch in the darkness. And this internal vision 
is exceptionally developed in somnambulists, who 
usually walk with their eyes closed and can avoid 
obstacles of every kind by their hyperaesthetic sense 
of touch. It is probable that if the somnambulist 
does not see by his eyes, he sees by reasoning. It 
is reasoning which, from the depths of the darkness, 
guides him by means of an internal light, formed 
by visual images. Thus we understand a multi- 
tude of improbable feats, how, for example, a cer- 
tain somnambulist can write a page of manuscript, 
read it over and correct it exactly, without the 
cooperation of sight. 

We are all acquainted with the thoroughly 
authentic story of an abbe who wrote sermons dur- 
ing his fits of natural somnambulism.* One day a 
white sheet was placed on the page of manuscript 
which he had just finished, and he re-read it on this 
white sheet, making erasures and corrections here 
and there which coincided exactly with the text 
below. In this case he had a most exact visual 
image of the written page, and he exteriorized that 
image on the sheet of paper, thus replacing sight 
by reasoning. These extreme cases give us the key 
to the normal state. 

It is more difificult to demonstrate directly that 
logical reasoning is like a supplementary sense, and 

*This observation is cited by Bersot, Mesmer et le magnetisttie animal, 
5th edition, p. 247. 



CONCL US /ON. 1 67 

that its purpose is to give us an internal vision* 
which protracts the external vision. In the syllo- 
gism the fact affirmed by the conclusion is too com- 
plex, too abstract, for the knowledge of it to appear 
comparable to a sensation. However, many 
authors have maintained an analogous thesis ; 
Schopenhauer said that the axioms of geometry 
are felt. We shall no longer have any doubt on 
this point, if we carefully observe what happens 
with hysterical subjects, those species of voyantcs 
who very often materialize the conclusions of their 
reasonings and make hallucinations out of them. 

One day we suggest to W , who is in the 

state of somnambulism, that she should make a ges- 
ture of contempt at a bust of Gall placed on a 
neighbouring table. f When she awakes she makes 
the gesture indicated, and seeking to explain the 
motive of this suggested act, which is for her spon- 
taneous and free, she says: "That bust is disgust- 
ing." This is a reasoned conclusion; but note that 
this conclusion takes the form of a hallucination; 
the patient sees the bust under a disgusting aspect, 
M. Fere has related this second example to me: 
We give, one day, to another patient the hallucina- 
tion of M. Fere, and we make her believe that she 
is fighting him ; during this imaginary combat the 
patient strikes his temple a vigorous blow with her 
fist, which stretches him on the ground. On the 
morrow the awakened patient sees M. Fere enter- 

*Here we take, for the sake of greater clearness, vision in place of all 
the senses, that is to say the species for the genus. 

tThe majority of the facts which we describe have been elucidated by 
us in the course of researches pursued in common with Dr. Fere at the Sal- 
petriere hospital. 



l6S THE PSrCIlOLOGl' OF REASONING. 

ing the ward, and she perceives that he carries a 
black-and-blue mark on his temple. This mark 
was produced by the imaginary blow which she had 
given him on the previous evening. Here again 
the conclusion of the reasoning culminates in vision. 
The patient performed the following unconscious 
reasoning: I have given him an extremely violent 
blow with my fist on his temple; therefore he must 
carry the mark of it. Hence the hallucination of 
an ecchymosis. Upon coming out of a phase of 
profound lethargy which has lasted five minutes at 
the most, a patient imagines that she has slept for 
several hours. We answer that it is two o'clock in 
the afternoon (it was really nine o'clock in the 
morning). The patient immediately feels the most 
acute hunger, and begs us to let her go and dine. 
Here again there is reasoning (it is late, therefore I 
am hungry) which produces as its conclusion a kind 
of organic hallucination, the hallucination of hunger. 
The preceding examples are unpublished ; the 
following are some others which have already been 
published, but the phenomenon has not yet been 
studied from the point of view at which we place 
ourselves. M. Richet suggests to Miss C- — ■ — , 
when she is in a trance, that she is going on board 
a packet boat, and that she is leaving for New York; 
soon the rolling of the boat makes itself felt, the 
woman becomes pale, and, throwing her head back, 
she has an attack of real nausea. This hallucina- 
tion is produced by the logical development which 
the subject causes the suggestion of a sea voyage 
to undergo ; this sickness is a conclusion from un- 



CONCLUSION. 169 

conscious reasoning: I am on a packet-boat, there- 
fore it rolls, therefore I am sick. M. Richet sug- 
gests to one of his friends that he is making a 
balloon ascent; the subject soon sees a huge shining 
ball in the distance ; it is the earth, a sight which 
he suggests to himself, and which is again a deduc- 
tion from the original suggestion. When he pre- 
pares to descend, M. Richet suggests that a piece 
of string is suspended down to the earth and that 
the subject should allow himself to slide down, 
holding on to the string with his hand. During this 
dangerous excursion the subject stopped suddenly, 
saying that the rope burned his hands. This is a 
fresh deduction which takes the hallucinatory form. 
The authors who comment upon facts of this 
kind see in them merely a manifestation of the 
association of ideas. It would be, they say, by 
association of ideas that the patient who believes 
herself to be on a steamer experiences nausea, etc. 
When they have pronounced that great word "asso- 
ciation," they think they have said everything. 
That is a mistake. Although there are hallucina- 
tions which are scarcely anything but recollections 
resuscitated under a sensible form, and in which 
the mind of the patient lets itself be guided by pre- 
established and completely formed associations, 
this is not a general rule. In other hallucinations 
it is quite the contrary ; the patient imagines, 
creates, invents an entire sensation, an object, an 
event, a scene or a picture, which is as new for 
him as for us, the witnesses. Far from confining 
himself to associations already formed, he makes 



170 THE PSrCHOLOGT OF REASONING. 

new ones, like that hallucinated subject who, rising 
in a balloon, sees the earth at his feet, although up 
to that day he had never made an aerostatic ascent. 
Now, this establishing of new associations, this 
construction of images according to a new plan, is 
really reasoning. But it is clear that between rea- 
soning and recollection there are all possible transi- 
tions, for reasoning is an application of a recollection 
to a datum which is new but similar; and that 
which predominates in the operation is the repro- 
duction of the recollection, or its new application, as 
the case may be. 

Here are some other facts which call for the same 
reflections. One of our patients, transformed by 
suggestion into a priest, sees himself, upon awaken- 
ing, dressed in a cassock which smells badly. A 
patient of M. Richet's, transformed into the Arch- 
bishop of Paris, spontaneously sees the President of 
the Republic, presents his New Year compliments 
to him, and hears the President replying in a low 
voice, ^'' eaii b^nite de cour.'" Another, transformed 
into a general, sees horses and aides-de-camp sur- 
rounding him, gives orders, reprimands, uses the 
telescope, etc. The curious thing is that when the 
subject is intelligent and imaginative, the sugges- 
tion which is directed towards him produces, not an 
isolated hallucination, but numerous hallucinations 
which form a picture. I may refer, in this connec- 
tion, to the examples mentioned by M. Paul Richer 
(hallucinations of a dinner in the country, of a fete, 
of an open-air ball, etc.)* In these examples we 

*0^. cii., passim. 



CONCLUSION. 171 

often seize, on the wing, the logical exercise of the 
mind which draws every possible deduction from 
the theme imposed upon it. Nothing is better 
suited to show that the purpose of reasoning is to 
create a kind of logical vision, so much the more 
striking as under these circumstances, logical — or in 
other words, hallucinatory — vision surpasses actual 
vision in intensity. 

The same phenomenon is frequently met with in 
mental alienation, when the insane person draws 
from a delirious conception a conclusion which 
assumes the hallucinatory form. Everybody knows 
the story of the man who, believing himself to be 
a king, took his rags for a royal mantle. A less- 
known case is that of a poor woman who, having 
one evening received, in a hallucination, a visit 
from her husband, had thereafter the hallucination 
of pregnancy. In this example one of the two 
hallucinations forms the premiss, and the second is 
the conclusion, and each conclusion becomes a hal- 
lucination. 

In our opinion, the hypnotic experiments which 
we have just described give a most beautiful 
demonstration of a phenomenon which is doubtful 
and almost altogether elusive in the normal state. 

We are inclined to believe that ordinary reason- 
ings culminate in a similar but less intense vision. 
We throw a stone into a pond. The stone, after 
having produced noisy splashes on the surface of 
the water, falls to the bottom, while around the 
point where it fell there forms a series of waves. 
Thence we infer by reasoning that another stone 



172 THE rSrCHOLOGT OF REASONING. 

thrown into the same pond, or into any mass of 
water, will produce the same effect on it. (Bain.) 
But in what does this conclusion consist? At the 
moment when, just before flinging the second 
stone, I infer the effect which it is going to pro- 
duce, what passes in my mind ? Is it not an inter- 
nal vision of the water, of the noisy splashes, and 
of those concentric waves which will be formed 
around the disturbed point? So the purpose of 
every reasoned conclusion appears to me to be to 
make us sec, by the mind's eye, the object or the 
fact which the conclusion affirms. The person who 
reasons, meditates in order to behold within 
himself, in a sort of magic lantern, the images 
which pass and the pictures which are formed. 
Reasoning produces a kind of logical vision which 
fills the gaps in actual vision ; it constructs a new 
universe in our mind on the model of the large. In 
short, such is the aim of knowledge: to know, to 
understand, to explain, to know the why and the 
how of things, all this culminates in an act of 
vision. The highest science is epitomized in these 
simple words : to see. 

Memory, which preserves the impressions of the 
senses, reproduces them at the necessary moment, 
and localizes them in their places in the picture of 
the past, might justly be called, like reasoning, a 
supplementary sense ; more exactly, memory is a 
vision of the past, while reasoning is, in general, a 
prevision — that is to say, a vision of the future. 

These conclusions are confirmed by the previous 
experiments on the consecutive image, which lead 



CONCLUSION. 173 

US to see in the visual centre a retina whose every 
point is represented in the peripheral retina. The 
expression "the mind's eye" ceases to be a meta- 
phor, and the field of the mind is as if counterdrawn 
from the visual field. In fact, while experimenting 
on the transferred consecutive image, we see that 
this image, which, like a recollection, is cerebral, 
has definite dimensions, height and depth, a right 
side and a left side, and a position in the field of 
vision, properties which prove to be common to all 
the images of the mind, and render the relation 
between the image and the sensation still more 
intimate. 

III. 

Three images which succeed each other, the 
first evoking the second by resemblance, and the 
second suggesting the third by contiguity — that is 
reasoning. Submit any reasoning to analysis, and 
you will find nothing else at the bottom of the 
crucible. But it would be an error to believe that 
this process belongs specially to reasoning. Far 
from it. We meet it in all intellectual operations; 
it is the single theme upon which nature has em- 
broidered the infinite variations of our thought. 

The two well-known laws of the association of 
ideas are at the basis of psychology. They are, 
according to John Stuart Mill, Mr. Bain and Mr. 
Sully, blended together in so intimate a fashion 
that neither of them can ever act alone. Let us 
consider a case of similarity properly so called, a 
portrait recalling the original ; in order that the two 



174 T'HB PSrCHOLOGT OF REASONING. 

similar images may not be confounded the one with 
the other, the second must present features which 
are sHghtly different; and how will these differ- 
ential characteristics be recalled? By contiguity. 
Here we recognize our three images and our two 
relations of resemblance and of contiguity. In 
order that a relation of resemblance may be per- 
ceived, it must be followed by a relation of conti- 
guity. Let us then examine a case of contiguity. 
What is necessary, asks Mr. Bain, in order that the 
sight of a river should recall its name to us? It is 
necessary that the actual impression made by the 
river restores, by virtue of similarity, the former 
impression of the river to which the former impres- 
sion of the name was contiguous. Suppose that 
this revival of the old idea of the river does not take 
place upon the new presentation, then the bond of 
contiguity will not have an opportunity to enter 
into play. 

In this case we again find our three images and 
our two relations. In order that a relation of con- 
tiguity may become known, it must be introduced 
by a relation of resemblance. 

How does it happen that these ideal recollec- 
tions are not reasonings, although they have their 
structure? To tell the truth, I do rot in the least 
know. Perhaps we ovight to appeal to what Lewes 
called the attitude of the mind ; in a simple associa- 
tion of ideas we only interest ourselves in the hint 
of a new image; in reasoning, on the contrary, we 
take more account of the association which this 
new image contracts with the preceding one. 



CONCLUSION. 175 

The formation of a general idea presen-ts the 
same phenomenon of iso'merisvi ; we know that it 
arises from the union of several particular images 
which are welded together by their common por- 
tions; the total operation is therefore composed of 
an association of resemblance followed by an asso- 
ciation of contiguity ; it is the same familiar pro- 
cess. But here we find, between the general idea 
and reasoning, a logical affinity which explains this 
unity of composition; the general idea is a reason- 
ing in embryo; to generalize any object is to affirm 
something in addition to the result of a single ex- 
perience. The general idea of a tree contains more 
elements than the vision of an isolated tree; it 
contains an implicit conclusion. 

All these phenomena are like the first outlines of 
reasoning. There are others, much more complex, 
which show the same mental composition. In 
order not to lose ourselves in too lengthy develop- 
ments of our subject, we shall remain within the 
limits of the study of external perception. 

So far, we have admitted that every perception 
results from a reasoning. This proposition is only 
true in general. In reality, many other acts may 
take the form of a perception — that is to say, man- 
ifest themselves directly after an impression of the 
senses. We may find in perception — first, an act 
of recollection ; second, an act of imagination. 

First. — There is no well-defined distinction be- 
tween a perception-recollection and a perception- 
reasoning. "To the psychologist," says Mr. Sully, 
"it comes to very much the same thing whether, 



I7<5 THE PSrCHOLOGT OF REASONING. 

for example, on a visit to Switzerland, our minds 
are occupied in perceiving the distance of a moun- 
tain or in remembering some pleasant excursion 
which we made to it on a former visit. In both 
cases there is a reinstatement of the past, a repro- 
duction of earlier experience, a process of adding 
to a present impression a product of imagination — 
taking this word in its widest sense. In both cases 
the same laws of reproduction or association are 
illustrated ; that is to say, an association of resem- 
blance followed by an association of contiguity." 
Further on the author adds a remark which proves 
how frequent this phenomenon is. "And our state 
of mind in recognizing an object or person is com- 
monly an alternation between these two acts of 
separating the mnemonic image from the percept 
and so recalling or recollecting the past, and fusing 
the image and the percept in what is specifically 
marked off as recognition."* 

In what respect does a recollection differ from a 
reasoning? This is difficult to determine. We 
grasp the analogies between these two acts much 
more easily than their differences. All that the 
most attentive observation teaches us is that some- 
times the suggested image is projected and localized 
in the panorama of the past, of which it appears to 
be a fragment, and sometimes it is referred to a 
present object, and throws off its character of old- 
ness, so as to appear actual. 

Second. — We have already spoken of imaginary 
perceptions. These are by no means rare facts, 

*0p. cit., p. 235. 



CONCLUSION. 177 

mere idle recreations; we necessarily see in them 
one of the forms of that desire for agreeable illu- 
sions which appears to be inveterate in us, for we 
meet it in the adult man, in the manifestations of 
art, in children, in their games (hide-and-seek, sham 
fighting, the doll, etc.), and even among young ani- 
mals, in their mimic combats. Analysis shows that 
these voluntary illusions are constructed according 
to the same processes as correct perceptions; an 
association of resemblance followed by an associa- 
tion of contiguity. As to their distinctive characters, 
they are only to be found in the attitude of tJie self 
which accompanies sensory perception. The mind 
knows that it has to deal with an illusion; it does 
not take it seriously. One understands that it 
would be extremely difficult to analyze so complex 
a psychical state. 

And now, how are we to explain this unity of 
composition among intellectual acts which have such 
different duties to perform? We believe that it is 
necessary to introduce the theory of evolution here. 
It seems to us probable that all psychical phenom- 
ena, so varied when we take them in the adult civil- 
ized man, have sprung from a common stock, and 
that they owe to that their unity of composition. 
But what can really be, in the three facts which we 
are comparing, the primitive fact to which the two 
others may be referred. It is that which is most 
necessary to the animial in its struggle for existence : 
reasoning. 

In fact, reasoning is, as we have said, a supple- 
mentary sense, freed from the conditions of time 



lyS THE PSrCHOLOGT OF REASONING. 

and space. We have by means of reasoning the 
sensation of external objects before they come into 
contact with our organism, which permits us to 
know in advance what conduct we must adopt; 
whether it concerns the animal in pursuit of food, 
in quest of the female, or in the interests of de- 
fence, reasoning, and perceptive reasoning in partic- 
ular, is the basis of a preadaptation of the individ- 
ual to its environment. 

Memory, as a vision into the past, offers less 
utility than reasoning; we have more frequent need 
to look before than behind ; it is a kind of intellect- 
ual refinement to contemplate the things of the past 
as past, and without making them serve in the 
explanation of present facts. Therefore it seems 
to us probable that memory is not a primitive, but 
a superadded fact ; it has sprung from reasoning at 
a time when the struggle for existence became less 
imperious. 

The same may be said of imagination, as a 
faculty of creating assemblages of images which do 
not correspond to any external reality. This 
faculty must belong to an advanced stage of devel- 
opment, for it is not directly useful in adaptation. 
Before taking pleasure in fictions, it was necessary 
to think of food, reproduction and defence. There- 
fore we must connect imagination with reasoning; 
it is reasoning deviated from its end, falsified, creat- 
ing chimeras which we do not seek to rectify, 
because they please us; thus a statue is a fiction of 
which we like to be the dupe. 

To sum up, all forms of mental activity are 



CONCLUSION. 179 

reducible to a single one — reasoning. The psy- 
chical life is a continual conclusion. Tlie mind, as 
Wundt says, is a tJmig which reasons. 

IV. 

The preceding theory explains reasoning by the 
properties of images and sensations, and by these 
properties alone. It introduces nothing else ; there- 
fore the expression "I reason," which is employed 
so often, is, taken literally, to a certain extent 
wrong. A collection of facts of consciousness — the 
self is nothing else — can have no action whatever 
on one fact of consciousness in particular. It is 
quite as incorrect to say that judgment is the act 
by which the mind compares. It is as if we said 
that chemical combination was the act by which 
chemistry unites two bodies. Just as the combina- 
tion of the bodies results directly from their proper- 
ties, so mental combinations, and reasoning in par- 
ticular, result directly from the properties of images. 

We may here repeat what M. Ribot has said of 
the voluntary act:* "The 'I will,' " he has re- 
marked, "testifies to a condition, but does not pro- 
duce it. The volition that subjective psychologists 
have so often observed, analyzed and commented 
upon, ... is not the cause of anything. 
The acts and movements which follow it result 
directly from the tendencies, feelings, images and 
ideas which have become coordinated in the form 
of a choice. It is from this group that all the efifi- 
cacy comes." The accuracy of this point of view 

*Diseases of the Will (Open Court Pub. Co., Chicago), p. 133. 



I So THE PSrCHOLOGT OF REASONING. 

is still more apparent, if that were possible, in the 
sphere of reasoning. The idea which we form of 
reasoning, the attributing of this operation to our 
self, to our personality, is a superadded phenome- 
non, and not an essential part of the operation. 
The "I reason" is not a cause, it is an effect. It is 
wanting in the child, in ignorant persons and in the 
millions of people who have never studied psy- 
chology. They have never tried to give an 
account of the fact that they reason, and of how 
they set about to reason. They are indifferent in 
the matter; they are content to reason without 
considering how they do it. 

The intransigeants of psychology, those who 
push everything to extremes, have maintained that 
we must say, It reasons in iny brain, as we say, It 
thunders in the sky. These expressions are not 
only ridiculous, they are inaccurate, which is worse. 
The formation of a self, as the centre and subject of 
all psychical phenomena, is not a matter of conven- 
tion ; it is a natural phenomenon, which is realized 
in every man. We must not therefore eliminate 
it. M. Richet has observed that in experiments on 
hypnotic suggestion, we may abolish and metamor- 
phose the personality of the subject without for all 
that suppressing his self, which proves that the two 
things are distinct. When we transform the sub- 
ject into a soldier, a dancer, a child, a bishop, or a 
goat, he adopts the language and the gestures of 
these different roles, but he does not cease to say 
"I" in speaking of his sensations and of his acts, 
to have a self — that is to say, a kind of point of 



CONCLUSION. l8l 

insertion for all the sensitive and motor impressions 
which take place within him. (Richet, La person- 
nalite et la inhnoire dans le soinnainbulisme, Revue 
philosopkigue, March, 1883.) 

So far nothing has been said of the principle or 
postulate which should be implied, according to 
many thinkers, in every kind of reasoning, and 
would justify the passage from the known to the 
unknown. The study of these principles holds an 
important place in treatises on logic. For example, 
the postulate of every induction would be the 
uniformity of the course of nature. In fact, it is 
said, in order to believe that what has been pro- 
duced in a particular case will be reproduced in all 
similar cases, it is necessary to believe previously 
that ''there are such things in nature as parallel 
cases; that what happens once, will, under a suffi- 
cient degree of similarity of circumstances, happen 
again, and not only again, but always."* 

It was long ago answered that the uniformity of 
the laws of nature was not taught us by a super- 
natural revelation ; it is a very complex piece of 
knowledge, which is wanting in the majority of 
men, and which, among those who possess it, is 
formed late, by a slow accumulation of partial 
inductions. To postulate the result of a particular 
induction, which is neither constant, nor elemen- 
tary, nor primitive, as the foundation of our induc- 
tions would therefore be to reason in a circle. 

The real foundation of reasoning must be 
sought in the psychical law which governs it. The 

*John Stuart Mill, Logic, Book III, Chap. III. 



1 82 THE PSrCHOLOGT OF REASONING. 

organization of our intelligence is so arranged that 
when the premisses of a reasoning are stated, the 
conclusion results from them with the necessity of 
a reflex action. In other words, we reason because 
we have in our brain a machine for reasoning. The 
legitimacy of our inferences has not a rational basis; 
it is not proved, for every demonstration presup- 
poses the legitimacy of the reasoning. This is a 
common sense truth. 

Let us be more precise ; in reasoning, the 
primary role belongs to the images ; it is the images 
which arrange themselves, in reasoning, by virtue 
of the properties which they manifest when they are 
brought before the mind ; it is they which sponta- 
neously form, to our internal sight, the picture of 
the external world. 

This conception is directly derived from the 
facts which fill this book. We have shown that 
similarity is a property of images, and we have said 
with M. Pilon that we must distinguish between 
the action of resemblance and the perception of 
resemblance. (See p. 127.) From this important 
distinction it follows that the suggestion of similar 
images is a primary fact of automatism; that the 
union and fusion of similar images into a generic 
image is a second fact of automatism ; and that the 
organization of similar images into reasoning is a 
third fact of automatism. In all these cases the 
self only intervenes when the work is finished. Just 
as "the resemblance between two images is only 
perceived after their suggestion" (Pilon), so the 



CONCL US ION. I §3 

reasoning which they form in becoming organized is 
only perceived after its formation. 

If it were necessary to make use of a comparison 
in order to describe the mechanism of reasoning, we 
would mention those flowers which are formed dur- 
ing frost on the window panes of rooms. Let us 
thaw them with our breath and then observe the 
regelation of the liquid layer. While crystallization 
is taking place round a first crystal "you notice one 
feature which is perfectly unalterable, and that is, 
angular magnitude. The spiculae branch from the 
trunk, and from these branches others shoot ; but 
the angles enclosed by the spiculae are unalter- 
able."* Just as these crystallizations are produced 
by the forces inherent in each of the molecules, so 
reasoning is produced by the properties inherent in 
each of the images; just as crystallization, in its 
oddest eccentricities, always observes a certain 
angular value, so reasoning, true, false or insane, 
always obeys the laws of resemblance and of conti- 
guity. 

This being admitted, reasoning may become 
unconscious without our being obliged to infer a 
profound change in the phenomena. When it is 
admitted that reasoning results from a faculty of 
the soul, is there any more embarrassing question 
than to explain the unconsciousness of certain 
reasonings? From our point of view nothing is 
more simple. Reasoning is a synthesis of images. 
Images are the psychical part of a psycho-physio- 
logical whole ; if they are wanting, the physiological 

*Tyndall, Light, p. loi; American Ed., p. 104. 



184 THE PSrCHOLOGT OF REASONING. 

process remains ; it alone is essential, and it is suffi- 
cient. The physiological mechanism acts, as if it 
were accompanied by its epiphenomenon, con- 
sciousness; it does its work noiselessly, and as 
surely arrives at the final result. 

We are not able to describe this physiological 
process. Here we are still in the region of hypoth- 
eses ; we append a schema which will serve merely 
to fix our ideas. To limit the question, let us take 
the visual perception of a particular object. 

Every perception implies anterior states which 
are preparatory to it. In order that we should be 
able to perceive the object which is before us, to 
recognize its nature, its use, etc., it is necessary 
that, through preceding experiences, we should have 
associated in our mind the visual image of this 
object or of another of the same kind, with the train 
of images of all sorts which constitute our knowl- 
edge of it. How shall we express the product of 
these anterior experiences in physiological terms? 
Images have the same cerebral seat as sensations; 
we may suppose that each of them results from the 
excitation of such and such a group of cells taken 
in the sensory centres of the surface layers. Let us 
denote the visual image of the object by «B; these 
two letters will represent the two cells of the centre 
of vision which are supposed to vibrate when we 
imagine the object visually; by C D E F G H 
we shall denote the cells which serve as substra- 
tum to the other images of the object, tactile, 
muscular, etc., images. 



C ONCL US ION. 1 85 

So far the hypothesis raises no difficulties. But 
we have so far eHminated an essential element, the 
relations. Psychological analysis proves that a 
bond of association exists between the different 
images of an object; it is this bond which gives the 
group its coherence and its unity, and which enables 
one of the attributes of an object to suggest the 
others, as when the voice of a person recalls his 
countenance. How can we translate this associa- 
tion physiologically? How are two impressions, of 
sight and hearing for instance, bound together in 
the brain? For that to be the case it is necessary 
that they be not restricted, the one to the visual 
centre and the other to the auditory centre. It has 
been assumed that when two groups of cells — the 
substratum of two images — are excited at the same 
time, the nervous wave circulates from one group 
to the other through those communicating fibres 
which are so numerous in the brain. So, as M. 
Fouillee says, do the two undulations produced in 
a mass of water by two stones dropped at a small 
distance apart come to meet each other. From 
this fact it follows that the path between the two 
groups of cells under consideration is rendered 
easier for future waves, and that when, later on, 
one of the two groups will be alone excited, the 
current leaving it will follow that way in preference 
to any other, as being the line of least resistance. 
(Spencer.) In this way the elementary fact of the 
association of ideas has been translated into physi- 
ological terms. It has been said that groups of 



lS6 THE PSYCHOLOGY OF REASONING. 

cells excited at the same time are united by dynam- 
ical associations (Ribot), or, again, form a single 
and individual clicJii. (Taine.) Thus in our 
example a dynamical association exists between the 
cells «B corresponding to the visual image of the 
object, and the cells C D E F G H corresponding 
to the mechanical sensations which the object gives 
when it is taken hold of. 

Let us add one touch more, and the hypothesis 
is complete. We have not spoken yet of the 
excitative sensation which must cause this associa- 
tion of cells to vibrate. Analysis has taught us 
that in external perception the sensation always 
resembles in part the first image which it evokes — 
that is to say, the anterior vision or visual recollec- 
tion of the same object, which we have denoted by 
^B. We may therefore denote the cells which will 
vibrate under the influence of the actual vision by 
the letters A*^. The small a in this formula is the 
name of the element common to the actual vision 
and to the past vision ; for we know that the psy- 
chical quality of resemblance has identity of seat 
as its physiological correlative. 

When the vision begins, the nervous wave, after 
having traversed the group of cells Ka, passes into 
the group «B, by means of the cellular junction 
afforded to it by the cell a. In psychological terms, 
the vision of the object first of all recalls, by simil- 
arity, its visual recollection. Then the nervous 
wave continues its path by means of the preestab- 
lished dynamical associations, and it spreads itself 



CONCLUSION. 1S7 

among the groups of cells denoted by C D E F 
G H ; at the same time the recollection of all the 
old experiences rises in the mind ; this wave of 
images becomes associated with the vision of the 
moment, and the psychical synthesis is formed. 

Certainly such a conception of the action of the 
nerve centres is a true hypothesis; we have no 
means whatever of observing what occurs in the 
brain of a thinking man. All that we can affirm is 
that reasoning might be effected by the mechanism 
described, for our neuro-physiological hypothesis is 
traced from the subjective analysis of reasoning. 
Thus reasoning might be defined from the physio- 
logical point of view as the continuation of a process 
whose first phase (the excitation of the cells Ad) is 
the only one which corresponds to an external stim- 
ulant. This is the counterpart of the psychological 
definition: reasoning is an extension of experience. 

We leave to the reader the care of deciding 
whether this mechanical theory removes all activity 
from the mind, so as to reduce it to a purely passive 
state. This is a reproach which has often been 
made against the English school, which tries to 
explain all the phenomena of the mind by the laws 
of association. But to what extent is this reproach 
well-founded? Images are not by any means dead 
and inert things; they have active properties; they 
attract each other, become connected and fused to- 
gether. It is wrong to make the image into a 
photographic stereotype, fixed and immutable. It is 
a living element, something which is born, some- 



l88 THE PSrCHOLOGT OF REASONING. 

thing which transforms itself, and which grows 
like one of our nails or our hairs. Mental activity 
results from the activity of images as the life of the 
hive results from the life of the bees, or, rather, as 
the life of an organism results from the life of its 
cells. 

THE END. 



INDEX. 



Achromatopsia, 34. 
Agraphia, 25. 
Alcoholic delirium, 134. 
Ampere, 121. 

Anaesthesia, systematised,73,76. 
Aphasia, motor, 25. 
Aristotle, 1, 87. 
Association, laws of, 92. 
Auditifs, 23. 

Baillarger, 48. 

Bain, Alexander, 4, 41, 43, 96, 

119, 144, 172, 173, 174. 
Ball, 61. 
Beclard, 44. 
Bersot, 166. 
Beyle, 115. 
Binet, 26, 43, 60, 73. 
Blindness, verbal, 26. 
Boole, 152. 
Brochard, 2, 90, 129. 
Brewster, 61. 

Charcot, 17, 27, 31. 
Chromatic contrast, 39. 
Circle of sensation, 105. 
Clifford, 112. 
Color blindness, 34. 
Coloured hallucinations, 35, 
Composite portraits, 116. 



Consciousness, intermediate 

state of, 139, 148. 
Contrast, chromatic, 39. 
Cycle, visual, 114. 

Da Vinci, Leonardo, 136. 
De Boismont, Brierre, 53. 
Delboeuf, 116. 
Delirium, alcoholic, 134. 
Diplopia, hallucinatory, 62. 

Euler, I. 

Evolution, theory of, 177. 
Experiment, mirror, 66. 
Experiments in hypnotism, 31. 

F^r^. 26, 39, 37, 40, 42, 61, 63, 

73. 167. 
Fouillee, 185. 
Fusion of similar images, the, 

113- 
Fusion, laws of, 108. 

Galton, II, 15, 24, 25. 113, 116, 

118. 
Genesis of external perception, 

129. 
Goethe, 114. 

Hallucinations, coloured, 35 ; 
hypnotic, 56 ; induced. 32 ; 



igo 



THE PSYCHOLOGY OF REASONING. 



suggested, 33 ; toxic, 135 ; 

visual, 38. 
Helmholtz, 8, 39, 50, 88, 143. 
Hemi-ansesthesia, 34. 
Henslow, Rev. George, 113. 
Huxley, 116. 
Hypnotism, experiments in, 31. 

Illusions, of the senses, 5, 60, 
89, 130; passive, 89; volun- 
tary, 177. 

Images, consecutive, 44, 172 ; 
consecutive and real, com- 
pared, 49; defined, 8, 31 ; dif- 
ferent kinds of, 13 ; generic, 
116; localisation of the, 37; 
motor, 24 ; physiology of the, 
31 ; physiological properties 
of, 43 ; psychological nature 
of, 10 ; seat of, 31 ; the fu- 
sion of similar, 113 ; theory 
of three, 158 ; sensations and, 
combination of, 68. 

Imagination, 178. 

Indifferents, 14. 

Induced hallucinations, 32. 

James, William, 24, 157. 
Janet, Paul, 2, 4. 

Lachelier, 5. 

Laird, Louis, 140. 

Lewes, 123. 

Localisation of the image, 37. 

Londe, 59. 

Lotze, 120. 

Magnan, 115, 135. 

Maury, 116, 129. 

Memory, 172, 178. 

Mill, John Stuart, i, 2, 79, 92, 



96, 98, 102, 144, 145, 152, 

154, 173, 181. 
Mirror experiment, 66. 
Moteurs, 23. 
Motor aphasia, 25. 
Motor image, 24. 

Nature, uniformity of the course 

of, 181. 
Nerve-fields, theory of, 106. 
Nev/ton, 48. 

Oscillations, consecutive, 42. 

Paraphrasia, 125. 

Parinaud, 39, 40, 44, 46, 47, >54. 

Paulhan, 29, 7b. 

Percept, 69, 78, 160. 

Perception, defined, 4, 8 ; dif- 
ferent kinds of, 70 ; external, 
56, 69, 81, 151 ; genesis of ex- 
ternal, 129; imaginary, 135; 
individual and generic, 73 ; 
mechanism of, 142 ; psycho- 
logical nature of, 80. 

Physiology of the image, 31. 

Pilon, 121, 127, 182. 

Portraits, composite, 116. 

Pouchet, 117. 

Properties of images, physiolo- 
gical, 43. 

Psychological nature of images, 
10. 

Reasoning, defined, 86, 93, 149; 
156 ; explanation of, 91 ; fac- 
ulty of, 95 ; formal, 81 ; foun- 
dation of, 181 ; function of, 
165 ; purpose of, 171 ; psy- 
chological mechanism of, 184 ."^ 
true theory of, 96 ; uncon- 
scious, 80. 



INDEX. 



191 



Renouvier, 157. 
Representations, 7. 
Retrogression, law of , 76. 
Ribot, 24, 76, 91, 96, 102, 124, 

179, 186. 
Richer, 52, 73, 82, 170. 
Richet, 168, 180. 

Schopenhauer, 167. 

Sensation, circle of, 105. 

Sensations and images, combi- 
nation of, 68. 

Senses, illusion of the, 5, 60, 
89, 130. 

Simon, Max, 115. 

Somnambulists, 166. 

Sophism, 89. 

Spencer, 43, 79, 84, 88, 93, 97, 
119, 125, 162, 185. 

Strieker, 27. 



Suggested hallucinations, 33. 
Sully, 70, 89, 116, 144, 173, 175. 
Syllogism, i, 80, 84, 97, 151, 
159, 162. 

Taine, 2, 10, 11, 15, 48, 60, 96, 

186. 
Toxic hallucinations, 133. 
Trousseau, 147. 

Verbal blindness, 26. 
Visual cycle, 1I4. 
Visual hallucination, 38. 

Weber, 103, 118. 
Wigan, 16. 

Wundt, 4, 40, 96, 121, 146, 156, 
179. 

Zootrope, 112. 



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